Millers 10W-50 Nano Oil - Good for our cars?
Discussion
monthefish said:
hartech said:
Gibbo - I am not at work today so will reply later in the week with the right specification we recommend - but our recommendations refer to typical road use and for track use it is important to fit a deeper sump and/or acusump if you corner aggressively - or you may lose oil pressure in long corners.
Baz
Hi Baz,Baz
For a 100k miles 996 3.4, would you put in Millers 10W-50 or Millers 5w-40?
Thanks.
bazhart said:
Because the M96/97 model range have open deck cylinders - they gradually migrate oval until they will eventually crack. During this time the piston clearance gradually increases. Furthermore the coolant flow is unbalanced one side of the engine to the other - so this gives rise to different expansion rates and temperatures in different parts of the engine.
The piston coating and Cylinder bore material is also unique to this model range.
Due to this (and various other factors) Millers recommended the 10/50 oil as the most suitable to cover all potential eventualities.
http://www.911uk.com/viewtopic.php?t=85575&postdays=0&postorder=asc&start=20The piston coating and Cylinder bore material is also unique to this model range.
Due to this (and various other factors) Millers recommended the 10/50 oil as the most suitable to cover all potential eventualities.
I know and trust Baz/Hartech and I'm happy to follow this advice.
ScienceTeacher said:
Doh! If only Baz had known! 40 years buidling engines and an international reputation as the foremost authority on M96/7 cars and a couple of years working with Millers to determine what works best and he gets it all wrong. I know which oil my 996 will be imbibing, and it's not Mobil 1.
Baz is not the foremost authority on M96/7 cars, even he'd admit that. Porsche are the foremost authority, they just don't want to admit/discuss their obvious (financially implicated) flaws. For what it's worth, the team certainly made an engine that's wonderful to use!I've owned a G1 987 3.4, and currently own a G1 997 3.8, both have been utterly wonderful cars whilst in my guardianship. Both 'imbibed/imbibe' respectively, Mobil 1 0W 40, and neither have ever given me any trouble.
hartech said:
Having regrettably got into quite an argument on another forum about this subject it seems that "which oil you use", "how you bring up your children", "politics" and "religion" are subjects people have such different views on - you can never win and should keep out of it if possible.
However I don't understand the logic of believing that the company that designed the engines we repair all day long know better than us when ours then do not fail after the modifications we have to carry out and the rebuilds nor that Porsche would not have commercial reasons for recommending certain product suppliers. Their recommended oils didn't stop bore scoring or IMS failures - and neither did they fix the problems by design improvements - but eventually had to rely on a whole new design to get out of trouble.
But guys and galls - I don't really care too much which oil you choose to use - I only know that we have a vested interest in using and recommending the very best available to our customers (for reputation and reliability) and that we could never have survived the consequences of the kind of problems that Porsche were big and remote enough to live through - so it is much more important for us to give the very best advice we can or all our livelihoods are at risk.
Baz
p.s. many thanks for all the supportive comments!!!!
Baz, did Porsche commission Hartech to design & manufacture the V4 in the 919 Hybrid? As you guys know better than them, added to fact that the 919H won the torturous 24h of Le Mans for two consecutive years, I thought Hartech might have been involved. There's no way idiotic Porsche could've built a car capable of winning LM24 two years in a row. Amazingly, Le Mans was won 7 times in a row back in the 80's! Can't remember the name of the company that achieved this amazing feat of endurance & reliabilty. However I don't understand the logic of believing that the company that designed the engines we repair all day long know better than us when ours then do not fail after the modifications we have to carry out and the rebuilds nor that Porsche would not have commercial reasons for recommending certain product suppliers. Their recommended oils didn't stop bore scoring or IMS failures - and neither did they fix the problems by design improvements - but eventually had to rely on a whole new design to get out of trouble.
But guys and galls - I don't really care too much which oil you choose to use - I only know that we have a vested interest in using and recommending the very best available to our customers (for reputation and reliability) and that we could never have survived the consequences of the kind of problems that Porsche were big and remote enough to live through - so it is much more important for us to give the very best advice we can or all our livelihoods are at risk.
Baz
p.s. many thanks for all the supportive comments!!!!
Gmund said:
ScienceTeacher said:
Doh! If only Baz had known! 40 years buidling engines and an international reputation as the foremost authority on M96/7 cars and a couple of years working with Millers to determine what works best and he gets it all wrong. I know which oil my 996 will be imbibing, and it's not Mobil 1.
Baz is not the foremost authority on M96/7 cars, even he'd admit that. Porsche are the foremost authority, they just don't want to admit/discuss their obvious (financially implicated) flaws. For what it's worth, the team certainly made an engine that's wonderful to use!I've owned a G1 987 3.4, and currently own a G1 997 3.8, both have been utterly wonderful cars whilst in my guardianship. Both 'imbibed/imbibe' respectively, Mobil 1 0W 40, and neither have ever given me any trouble.
It's people like you that ruin these types of discussions of the rest of us. It can't be disputed that Baz has a lot of experience with these engines and his posts are helpful to the wider community, but I can see why he gets upset when he posts and then gets this type of response.
Porsche designed the M96/7 engines not Baz. The engines have their issues which Porsche weren't clever enough to predict during the design.
Porsche will not spend a lot of time 'looking back' because, as an OEM, they are in business to make future cars and it won't be economically viable to commit a lot of resource to looking back at product lines that are no longer in production and, more importantly, no longer within any warranty period.
So I would wager Baz would know at least as much as Porsche, and probably more, about the root cause(s) of the engine failures.
Just realised this old chestnut has reared its head again.
Despite the sarcasm we do not of course remotely suggest we know more than Porsche nor could have designed or run cars to win the Championships that they did (for which some rather obvious financial differences impact), however manufacturers design and build to a price and a market and try new technology where they believe it will make the product better or their own margins larger.
Porsche knew how to make closed deck engines with Nikasil alloy liners (GT3 and Turbo's) - but charged much more for them and tried Lokasil in the less expensive N/A Boxster, Cayman, 996 and 997 examples. They almost got away with it (as most are still reliable and especially with the smaller capacity variants) but suffered greater failure rates than the public (or them I suspect) would have anticipated - so reverted to another previously successful technology for the Gen 2 engines (almost certainly costing them a little more and reducing margins).
We simply recognised the weaknesses early on and invested in making our repair system efficient and applied the same technology as Porsche already used in the GT3 and turbo's of a Nikasil alloy liner in a closed deck assembly. Not exactly rocket science just providing a higher quality proven solution and doing it in a flow production system and with new specialised machinery and highly experienced and trained staff. After initially manufacturing our own liners - as quantities increased to over a thousand/year - we also sub-contracted that manufacture to a highly respected F1 supplier with the greatest reputation.
But for the money and reorganisation we put into our top quality repairs - our solution may have become too expensive (compared to inferior alternatives) but that early effort has enabled us to supply this to the market at about the same price others charge for discredited and out of date technology resulting in us still expanding and supplying to Worldwide markets (now including North America).
So - we do not inflate our own ego's by imagining we are superior to Porsche at all - perhaps we just built the engines to the specification they could have done first time with obvious benefits.
Having said that - by way of answering sarcasm - would you over critical posters allow me to be a bit cheeky and big headed and counter that criticism by simply stating a few facts that many years ago now (1) I designed, manufactured and built a three cylinder 350 motorcycle that first time it was ever on a track - Barry Sheene tested at Brands Hatch (breaking the lap record), The 500cc Sparton engine that first time in a race was the fastest at the IOM TT and amongst numerous International wins was 1st and second in the North West 200 (Britains fastest road race) and The 750cc Phoenix 4 engine that won several TT races (and powered David Essex's Silver Dream Racer (and the whole bike) - all achieved without use of a dyno at that time. Then with a dyno to develop the engines - the 350 cc in line twin with the World's first fully carbon fibre chassis that ridden by Nial McKenzie won the British Championship twice and finished 3rd in the World Championship French GP, was responsible for the 250cc Armstrong that won a GP and designed and manufactured various upgrades for Susuki works racers, Nortons, Ducatis, Kawasakis and Hondas.
Before you are too sick of me - I also revolutionised the production of the Rolls Royce RB211 fan blade blanks and turned around a number of local aerospace and automotive businesses before starting up Hartech.
It will therefore not come as a surprise that despite having no previous motor racing experience - when we entered motor racing in the Porsche Club Championship we didn't buy success by sourcing a winning car but built our own from scratch and had a win at our first ever meeting and despite pulling out two years ago our cars still hold the lap records at all the circuits. Furthermore - to counter suspicion that our engines were illegal I arranged for them to be sealed and at the end of the season - stripped - thoroughly inspected and declared totally standard.
All this achieved with a team of 3 or 4 people while earning a living doing something else and with limited funding that in comparison to the likes of those who we beat (most of the Japanese motorcycle industry) and up against motor racing teams with years of experience - is something to be proud of.
So - yes not claiming to be anything like as capable or experienced as Porsche - but also not a bunch of amateurs and deserving of more respect than that trotted out above! (Short video @ www.hartech.org demonstrates much of the above).
Baz (embarrassed and self conscious at posting this but annoyed at the disrespect posted) - sorry! please forgive this lapse of modesty.
Despite the sarcasm we do not of course remotely suggest we know more than Porsche nor could have designed or run cars to win the Championships that they did (for which some rather obvious financial differences impact), however manufacturers design and build to a price and a market and try new technology where they believe it will make the product better or their own margins larger.
Porsche knew how to make closed deck engines with Nikasil alloy liners (GT3 and Turbo's) - but charged much more for them and tried Lokasil in the less expensive N/A Boxster, Cayman, 996 and 997 examples. They almost got away with it (as most are still reliable and especially with the smaller capacity variants) but suffered greater failure rates than the public (or them I suspect) would have anticipated - so reverted to another previously successful technology for the Gen 2 engines (almost certainly costing them a little more and reducing margins).
We simply recognised the weaknesses early on and invested in making our repair system efficient and applied the same technology as Porsche already used in the GT3 and turbo's of a Nikasil alloy liner in a closed deck assembly. Not exactly rocket science just providing a higher quality proven solution and doing it in a flow production system and with new specialised machinery and highly experienced and trained staff. After initially manufacturing our own liners - as quantities increased to over a thousand/year - we also sub-contracted that manufacture to a highly respected F1 supplier with the greatest reputation.
But for the money and reorganisation we put into our top quality repairs - our solution may have become too expensive (compared to inferior alternatives) but that early effort has enabled us to supply this to the market at about the same price others charge for discredited and out of date technology resulting in us still expanding and supplying to Worldwide markets (now including North America).
So - we do not inflate our own ego's by imagining we are superior to Porsche at all - perhaps we just built the engines to the specification they could have done first time with obvious benefits.
Having said that - by way of answering sarcasm - would you over critical posters allow me to be a bit cheeky and big headed and counter that criticism by simply stating a few facts that many years ago now (1) I designed, manufactured and built a three cylinder 350 motorcycle that first time it was ever on a track - Barry Sheene tested at Brands Hatch (breaking the lap record), The 500cc Sparton engine that first time in a race was the fastest at the IOM TT and amongst numerous International wins was 1st and second in the North West 200 (Britains fastest road race) and The 750cc Phoenix 4 engine that won several TT races (and powered David Essex's Silver Dream Racer (and the whole bike) - all achieved without use of a dyno at that time. Then with a dyno to develop the engines - the 350 cc in line twin with the World's first fully carbon fibre chassis that ridden by Nial McKenzie won the British Championship twice and finished 3rd in the World Championship French GP, was responsible for the 250cc Armstrong that won a GP and designed and manufactured various upgrades for Susuki works racers, Nortons, Ducatis, Kawasakis and Hondas.
Before you are too sick of me - I also revolutionised the production of the Rolls Royce RB211 fan blade blanks and turned around a number of local aerospace and automotive businesses before starting up Hartech.
It will therefore not come as a surprise that despite having no previous motor racing experience - when we entered motor racing in the Porsche Club Championship we didn't buy success by sourcing a winning car but built our own from scratch and had a win at our first ever meeting and despite pulling out two years ago our cars still hold the lap records at all the circuits. Furthermore - to counter suspicion that our engines were illegal I arranged for them to be sealed and at the end of the season - stripped - thoroughly inspected and declared totally standard.
All this achieved with a team of 3 or 4 people while earning a living doing something else and with limited funding that in comparison to the likes of those who we beat (most of the Japanese motorcycle industry) and up against motor racing teams with years of experience - is something to be proud of.
So - yes not claiming to be anything like as capable or experienced as Porsche - but also not a bunch of amateurs and deserving of more respect than that trotted out above! (Short video @ www.hartech.org demonstrates much of the above).
Baz (embarrassed and self conscious at posting this but annoyed at the disrespect posted) - sorry! please forgive this lapse of modesty.
I have been running Millers Nanodrive CFS for 60k (in a diesel Scirocco but it's abused nevertheless).
OEM spec oil is 5w30.
I changed to 5w40 for better hot wear protection
I now run 10w50 and it's fine and oil temps are reduced. As Mr Hartech says the nano particles in the oil basically stop wear and it is a very good oil.
If you are concerned about wear when cold just allow the engine 1 or 2 minutes to idle before driving.
OEM spec oil is 5w30.
I changed to 5w40 for better hot wear protection
I now run 10w50 and it's fine and oil temps are reduced. As Mr Hartech says the nano particles in the oil basically stop wear and it is a very good oil.
If you are concerned about wear when cold just allow the engine 1 or 2 minutes to idle before driving.
xjay1337 said:
I have been running Millers Nanodrive CFS for 60k (in a diesel Scirocco but it's abused nevertheless).
OEM spec oil is 5w30.
I changed to 5w40 for better hot wear protection
I now run 10w50 and it's fine and oil temps are reduced. As Mr Hartech says the nano particles in the oil basically stop wear and it is a very good oil.
If you are concerned about wear when cold just allow the engine 1 or 2 minutes to idle before driving.
How much temp/reduction in viscosity do you think 1-2 mins will make?! Check out the viscosity indices of some of the popular oils and even for the same SAE grade, they can be very differentOEM spec oil is 5w30.
I changed to 5w40 for better hot wear protection
I now run 10w50 and it's fine and oil temps are reduced. As Mr Hartech says the nano particles in the oil basically stop wear and it is a very good oil.
If you are concerned about wear when cold just allow the engine 1 or 2 minutes to idle before driving.
My German engine builder used to religiously use Mobil 1 as specified by Porsche but now uses Motul 300V in tuned/race engines. In my GT2 built engine I use Motul 300V 15/50, it seems a very sophisticated oil, pours like a 0-40 but has high resistance to dilution and can take high power.
Having said the above I put in Millers CFS 10-50 for the winter because I fancied the 10 bit for our arctic winter conditions and the blurb on it seems convincing.
I had analysis done on each type at about 4000 miles and you can see they look pretty much the same, the only bit I thought interesting was the kinematic viscosity at 100 deg C
Motul quote 17.8 and measured after 4000 miles was 18.68
Millers quote 19.8 and measured after 4000 miles was 16.55
Does this mean that the Motul will stay more stable at high load high temp after 4000 miles than the Millers ? I have no idea and the numbers are pretty close.
Having said the above I put in Millers CFS 10-50 for the winter because I fancied the 10 bit for our arctic winter conditions and the blurb on it seems convincing.
I had analysis done on each type at about 4000 miles and you can see they look pretty much the same, the only bit I thought interesting was the kinematic viscosity at 100 deg C
Motul quote 17.8 and measured after 4000 miles was 18.68
Millers quote 19.8 and measured after 4000 miles was 16.55
Does this mean that the Motul will stay more stable at high load high temp after 4000 miles than the Millers ? I have no idea and the numbers are pretty close.
fergus said:
How much temp/reduction in viscosity do you think 1-2 mins will make?! Check out the viscosity indices of some of the popular oils and even for the same SAE grade, they can be very different
Well I have oil temperature gauge and it will happily climb 8-10 degrees at idle in 2 minutes.The main part would be lubricating the engine parts if they are slow to receive oil due to increased weight.
Regarding the kinematic viscosity, I can't answer factually but I understand that Millers tries to reduce friction as it gets hotter.
I admit to not understanding as much about oils as many contributors do.
From my limited knowledge - there are two basic types of viscosity measurement taken at different temperatures - dynamic (measuring the resistance to squashing the oil film thickness under pressure) and Kinematic (the speed of flow or sheer resistance) the latter being how we did it at University by measuring the flow rate through an orifice at different temperatures - and I understand this is the most commonly used in comparisons.
The Kinematic viscosity of Millers CFS 10W60 racing oil is 24.3 cSt @ 100 deg C and 170.8 cSt @ 40 deg.
The Kinematic viscosity of Millers CFS 10W50 racing oil is 19.8 cSt @ 100 deg C and 131.5 cSt @ 40 deg.
This clearly shows how the viscosity increases the resistance to flow as the rating is higher.
I have found it very difficult to obtain comparative figures for Mobil 1 but if I understand it correctly (which I may not) - you would have to go to a grade of oil viscosity for Mobil 1 of between 150 and 220 to obtain similar performance (I would welcome some confirmation of this or an alternative source of information to get a true comparison).
However - all this is in my opinion of little bearing on the problem of bore scoring because it seems to assume that the coolant temperature is the same thing as the temperature of the oil film between the piston and the cylinder bore - which it is not.
Piston Crowns run generally at anything up to 300 degrees C and the heat is dissipated down the piston skirts and through the oil film to the cylinder wall and through that to the coolant. At every "interchange" the transferred temperature is less than the source temperature and so the skirt of the piston in contact with the oil film is very much hotter. That temperature is affected by how much power the engine is producing (or if you like throttle opening) and the temperature of the coolant inside the cylinder block next to the outside of the cylinder wall - the cooler that is - the cooler the internal oil film temperature and film strength.
Unlike most other traditional Porsche liquid cooled engines (and Gen 2 engines) only about 15% of the coolant passes through the cylinder block and 85% through the cylinder heads - after which it mixes together again.
So - even if the temperature gauge read true this would not be the cylinder block coolant temperature because it is reading the mixture of all the coolant after it has been directed through the cylinders (which are hotter and only around 15% of the total) and is mixed back with the coolant from the cylinder heads (85%) and it would be the mixed result of the two different temperatures that the gauge would read and not the temperature of the upper cylinder that we are concerned about.
Indeed with such a small proportion of the cylinder block coolant being in the mix any changes in cylinder block temperature would be largely masked by and dominated by the more constant cylinder head coolant temperature. For example if 15% of the coolant (in the block) was at 80 degrees and 85% (in the head) was at 85 degrees the resulting mixed temperature read by the gauge would be 84.25 degrees – but if 15% of the coolant in the cylinder block went up to 110 degrees and the cylinder heads remained at 85 degrees the resultant mix would only be at 88.75 degrees and the temperature gauge would still read the same for both circumstances because it is buffered. So a 30 degree rise in cylinder block temperature would only increase the temperature of the mixed coolant going to the radiators by 4.5 degrees, not be noticed on the temperature gauge and result in a thermostat reacting slowly to the small rise in temperature.
As I interpret this it means that if after a spirited run the car has to stop somewhere ticking over (say at traffic lights) the heat soak into the engine would go up but the coolant flow would almost stop (because the coolant pump is running slowly) the air flow through the radiator would stop (because it is stationary), the oil splash into the cylinders (from the crankshaft rotating) and the oil pressure is lower (reducing the oil spray through the oil spray jets into the under side of the piston that cool the piston) - so there would be a very high temperature rise in the area of the piston and cylinder wall increasing the temperature of the oil film there dramatically and reducing the oil viscosity just there by a large margin.
The most critical area for good film strength between the piston and the cylinder wall is on the "thrust face" and this is on the underneath of the piston on bank 1 and the top of the piston on bank 2.
Now the most efficient cooling is with "contra-flow" (where the coolest coolant hits the hottest components first and heats up as it passes towards the less hot areas). We have this on bank 1 because the coolant enters at the bottom of the cylinder where the thrust face is but the opposite is true on bank 2 where the coolant also enters at the bottom and is therefore hotter when it reaches the thrust side of the piston - on the top.
The affect of this is exacerbated when the coolant flow is low (as in a stationary stop).
All this means that the temperature of the oil film at the top of the piston on bank 2 will be much hotter than that on bank 1 - the oil will therefore be very much thinner and the film strength and thickness will be much less.
Now any particle degradation that releases a particle of silicon from the cylinder wall allows it to sit stuck in between the cylinder wall and the piston and the thickness of the oil film is the only thing that can help prevent it digging into the piston coating and/or cylinder wall. It is also a recorded fact that the size of those particles can be as large as the piston clearance (or more especially in any Lokasil 2 engines which are likely to be the later more powerful engines). A harder piston coating will of course help the piston survive (as was applied to early Boxsters and most 996 3.4 engines except the last ones), whereas engines with softer plastic coated pistons will suffer sooner (as fitted to later Boxster, Cayman, 996 3.6 and 997 Gen 1 engines).
The higher the power the greater the squeeze thinning the oil film and the quicker it thins in one power stroke - so bigger engines should suffer more (and they do the 3.8 being the most common to score bores)
The pressure forcing the oil film between the piston and the cylinder wall to squeeze thinner still is proportional to the torque (or perhaps throttle opening) - so in this particular engine - we have a scenario in which - if we drive the car too hard immediately after a hot stop (and before the coolant and oil temperatures have had an opportunity to reduce through the increased revs and air flow through the radiators) we will increase the risk of those silicon particles impinging on the piston coating or cylinder wall and instigating bore scoring (hence our advice to avoid it and run without high throttle openings until the system has had a chance to cool down again and increase that oil film thickness through reduced temperatures).
Now this is of course true of all engines except this one is almost unique in the fact that the coolant proportions into the cylinder block are so small and the flow allows bank 2 to run hotter on the thrust side than bank 1.
We carried out a lot of tests with temperature sensors inside different parts of the cylinder block that substantiated all of these findings but it would have been nice if we could have fitted some sophisticated temperature sensitive measuring device right up against the cylinder wall during our tests that measured by how much those localised temperatures increased in different scenarios (unfortunately beyond our resources).
Never the less - if this analysis was true then we would expect engines to fail on bank 2 first and perhaps bank 1 many years an thousands of miles later - and this is exactly what we have found where one or two of those customers who only had one scored cylinder replaced (or perhaps just all three on bank 2) say 5 or 6 years ago - are now experiencing bore scoring on bank 1 (as we predicted they would).
Fortunately the vast majority of customers have all 6 replaced now (for which we discount the cost through efficiency benefits in set-up times etc) and so experience no further cylinder problems.
Ok you may ask - what has this got to do with oil types makes and viscosities?
Well it seems to me that this unusual system that runs the thrust face of one bank so much hotter than the other (or most other engines) in this stop/start scenario would require a thicker (or higher viscosity) oil to be fed to the cylinder wall areas to protect it better.
The crankshaft shell bearings are also quite thin in comparison to many other engines of similar power output and show signs of early wear when engines have been used more aggressively than other less aggressive customers (because the rate that oil is squeezed out of the gap between the shells and the crankshaft has a proportionality to load or force) and once again a thicker oil would help to protect them longer.
It would therefore be good if it were theoretically possible to send a thicker oil to the crankshaft and cylinders than the rest of the engine - but we cannot. So what is the down side of a compromise of using a thicker oil?
Minutely higher fuel consumption? slightly longer to reach operating temperatures before driving fast? slightly more friction drag? and the question is - which is more important - that minute down side or protecting the engine to last longer before it needs a rebuild?
Because of this - oils that have a higher viscosity rating seem to me to be a more sensible to use and those with added technical benefits as the temperatures rise (like Millers - although there may well be others) must be a good idea.
Thinner oils will reduce that oil film thickness and strength much more under those sudden temperature increases (that we cannot measure or see on the temperature gauge but absolutely do occur inside the engine under stop/start conditions).
That's my take on the situation but I would be interested in the contribution of those that specialise in oils and related subjects and how they see my analysis working with different products and in the light of experience and particularly when there is a critical part of an engine that runs much hotter than the rest of it or most other engine types.
Baz
From my limited knowledge - there are two basic types of viscosity measurement taken at different temperatures - dynamic (measuring the resistance to squashing the oil film thickness under pressure) and Kinematic (the speed of flow or sheer resistance) the latter being how we did it at University by measuring the flow rate through an orifice at different temperatures - and I understand this is the most commonly used in comparisons.
The Kinematic viscosity of Millers CFS 10W60 racing oil is 24.3 cSt @ 100 deg C and 170.8 cSt @ 40 deg.
The Kinematic viscosity of Millers CFS 10W50 racing oil is 19.8 cSt @ 100 deg C and 131.5 cSt @ 40 deg.
This clearly shows how the viscosity increases the resistance to flow as the rating is higher.
I have found it very difficult to obtain comparative figures for Mobil 1 but if I understand it correctly (which I may not) - you would have to go to a grade of oil viscosity for Mobil 1 of between 150 and 220 to obtain similar performance (I would welcome some confirmation of this or an alternative source of information to get a true comparison).
However - all this is in my opinion of little bearing on the problem of bore scoring because it seems to assume that the coolant temperature is the same thing as the temperature of the oil film between the piston and the cylinder bore - which it is not.
Piston Crowns run generally at anything up to 300 degrees C and the heat is dissipated down the piston skirts and through the oil film to the cylinder wall and through that to the coolant. At every "interchange" the transferred temperature is less than the source temperature and so the skirt of the piston in contact with the oil film is very much hotter. That temperature is affected by how much power the engine is producing (or if you like throttle opening) and the temperature of the coolant inside the cylinder block next to the outside of the cylinder wall - the cooler that is - the cooler the internal oil film temperature and film strength.
Unlike most other traditional Porsche liquid cooled engines (and Gen 2 engines) only about 15% of the coolant passes through the cylinder block and 85% through the cylinder heads - after which it mixes together again.
So - even if the temperature gauge read true this would not be the cylinder block coolant temperature because it is reading the mixture of all the coolant after it has been directed through the cylinders (which are hotter and only around 15% of the total) and is mixed back with the coolant from the cylinder heads (85%) and it would be the mixed result of the two different temperatures that the gauge would read and not the temperature of the upper cylinder that we are concerned about.
Indeed with such a small proportion of the cylinder block coolant being in the mix any changes in cylinder block temperature would be largely masked by and dominated by the more constant cylinder head coolant temperature. For example if 15% of the coolant (in the block) was at 80 degrees and 85% (in the head) was at 85 degrees the resulting mixed temperature read by the gauge would be 84.25 degrees – but if 15% of the coolant in the cylinder block went up to 110 degrees and the cylinder heads remained at 85 degrees the resultant mix would only be at 88.75 degrees and the temperature gauge would still read the same for both circumstances because it is buffered. So a 30 degree rise in cylinder block temperature would only increase the temperature of the mixed coolant going to the radiators by 4.5 degrees, not be noticed on the temperature gauge and result in a thermostat reacting slowly to the small rise in temperature.
As I interpret this it means that if after a spirited run the car has to stop somewhere ticking over (say at traffic lights) the heat soak into the engine would go up but the coolant flow would almost stop (because the coolant pump is running slowly) the air flow through the radiator would stop (because it is stationary), the oil splash into the cylinders (from the crankshaft rotating) and the oil pressure is lower (reducing the oil spray through the oil spray jets into the under side of the piston that cool the piston) - so there would be a very high temperature rise in the area of the piston and cylinder wall increasing the temperature of the oil film there dramatically and reducing the oil viscosity just there by a large margin.
The most critical area for good film strength between the piston and the cylinder wall is on the "thrust face" and this is on the underneath of the piston on bank 1 and the top of the piston on bank 2.
Now the most efficient cooling is with "contra-flow" (where the coolest coolant hits the hottest components first and heats up as it passes towards the less hot areas). We have this on bank 1 because the coolant enters at the bottom of the cylinder where the thrust face is but the opposite is true on bank 2 where the coolant also enters at the bottom and is therefore hotter when it reaches the thrust side of the piston - on the top.
The affect of this is exacerbated when the coolant flow is low (as in a stationary stop).
All this means that the temperature of the oil film at the top of the piston on bank 2 will be much hotter than that on bank 1 - the oil will therefore be very much thinner and the film strength and thickness will be much less.
Now any particle degradation that releases a particle of silicon from the cylinder wall allows it to sit stuck in between the cylinder wall and the piston and the thickness of the oil film is the only thing that can help prevent it digging into the piston coating and/or cylinder wall. It is also a recorded fact that the size of those particles can be as large as the piston clearance (or more especially in any Lokasil 2 engines which are likely to be the later more powerful engines). A harder piston coating will of course help the piston survive (as was applied to early Boxsters and most 996 3.4 engines except the last ones), whereas engines with softer plastic coated pistons will suffer sooner (as fitted to later Boxster, Cayman, 996 3.6 and 997 Gen 1 engines).
The higher the power the greater the squeeze thinning the oil film and the quicker it thins in one power stroke - so bigger engines should suffer more (and they do the 3.8 being the most common to score bores)
The pressure forcing the oil film between the piston and the cylinder wall to squeeze thinner still is proportional to the torque (or perhaps throttle opening) - so in this particular engine - we have a scenario in which - if we drive the car too hard immediately after a hot stop (and before the coolant and oil temperatures have had an opportunity to reduce through the increased revs and air flow through the radiators) we will increase the risk of those silicon particles impinging on the piston coating or cylinder wall and instigating bore scoring (hence our advice to avoid it and run without high throttle openings until the system has had a chance to cool down again and increase that oil film thickness through reduced temperatures).
Now this is of course true of all engines except this one is almost unique in the fact that the coolant proportions into the cylinder block are so small and the flow allows bank 2 to run hotter on the thrust side than bank 1.
We carried out a lot of tests with temperature sensors inside different parts of the cylinder block that substantiated all of these findings but it would have been nice if we could have fitted some sophisticated temperature sensitive measuring device right up against the cylinder wall during our tests that measured by how much those localised temperatures increased in different scenarios (unfortunately beyond our resources).
Never the less - if this analysis was true then we would expect engines to fail on bank 2 first and perhaps bank 1 many years an thousands of miles later - and this is exactly what we have found where one or two of those customers who only had one scored cylinder replaced (or perhaps just all three on bank 2) say 5 or 6 years ago - are now experiencing bore scoring on bank 1 (as we predicted they would).
Fortunately the vast majority of customers have all 6 replaced now (for which we discount the cost through efficiency benefits in set-up times etc) and so experience no further cylinder problems.
Ok you may ask - what has this got to do with oil types makes and viscosities?
Well it seems to me that this unusual system that runs the thrust face of one bank so much hotter than the other (or most other engines) in this stop/start scenario would require a thicker (or higher viscosity) oil to be fed to the cylinder wall areas to protect it better.
The crankshaft shell bearings are also quite thin in comparison to many other engines of similar power output and show signs of early wear when engines have been used more aggressively than other less aggressive customers (because the rate that oil is squeezed out of the gap between the shells and the crankshaft has a proportionality to load or force) and once again a thicker oil would help to protect them longer.
It would therefore be good if it were theoretically possible to send a thicker oil to the crankshaft and cylinders than the rest of the engine - but we cannot. So what is the down side of a compromise of using a thicker oil?
Minutely higher fuel consumption? slightly longer to reach operating temperatures before driving fast? slightly more friction drag? and the question is - which is more important - that minute down side or protecting the engine to last longer before it needs a rebuild?
Because of this - oils that have a higher viscosity rating seem to me to be a more sensible to use and those with added technical benefits as the temperatures rise (like Millers - although there may well be others) must be a good idea.
Thinner oils will reduce that oil film thickness and strength much more under those sudden temperature increases (that we cannot measure or see on the temperature gauge but absolutely do occur inside the engine under stop/start conditions).
That's my take on the situation but I would be interested in the contribution of those that specialise in oils and related subjects and how they see my analysis working with different products and in the light of experience and particularly when there is a critical part of an engine that runs much hotter than the rest of it or most other engine types.
Baz
Edited by hartech on Friday 5th August 12:12
hartech said:
Just realised this old chestnut has reared its head again.
Despite the sarcasm we do not of course remotely suggest we know more than Porsche nor could have designed or run cars to win the Championships that they did (for which some rather obvious financial differences impact), however manufacturers design and build to a price and a market and try new technology where they believe it will make the product better or their own margins larger.
Porsche knew how to make closed deck engines with Nikasil alloy liners (GT3 and Turbo's) - but charged much more for them and tried Lokasil in the less expensive N/A Boxster, Cayman, 996 and 997 examples. They almost got away with it (as most are still reliable and especially with the smaller capacity variants) but suffered greater failure rates than the public (or them I suspect) would have anticipated - so reverted to another previously successful technology for the Gen 2 engines (almost certainly costing them a little more and reducing margins).
We simply recognised the weaknesses early on and invested in making our repair system efficient and applied the same technology as Porsche already used in the GT3 and turbo's of a Nikasil alloy liner in a closed deck assembly. Not exactly rocket science just providing a higher quality proven solution and doing it in a flow production system and with new specialised machinery and highly experienced and trained staff. After initially manufacturing our own liners - as quantities increased to over a thousand/year - we also sub-contracted that manufacture to a highly respected F1 supplier with the greatest reputation.
But for the money and reorganisation we put into our top quality repairs - our solution may have become too expensive (compared to inferior alternatives) but that early effort has enabled us to supply this to the market at about the same price others charge for discredited and out of date technology resulting in us still expanding and supplying to Worldwide markets (now including North America).
So - we do not inflate our own ego's by imagining we are superior to Porsche at all - perhaps we just built the engines to the specification they could have done first time with obvious benefits.
Having said that - by way of answering sarcasm - would you over critical posters allow me to be a bit cheeky and big headed and counter that criticism by simply stating a few facts that many years ago now (1) I designed, manufactured and built a three cylinder 350 motorcycle that first time it was ever on a track - Barry Sheene tested at Brands Hatch (breaking the lap record), The 500cc Sparton engine that first time in a race was the fastest at the IOM TT and amongst numerous International wins was 1st and second in the North West 200 (Britains fastest road race) and The 750cc Phoenix 4 engine that won several TT races (and powered David Essex's Silver Dream Racer (and the whole bike) - all achieved without use of a dyno at that time. Then with a dyno to develop the engines - the 350 cc in line twin with the World's first fully carbon fibre chassis that ridden by Nial McKenzie won the British Championship twice and finished 3rd in the World Championship French GP, was responsible for the 250cc Armstrong that won a GP and designed and manufactured various upgrades for Susuki works racers, Nortons, Ducatis, Kawasakis and Hondas.
Before you are too sick of me - I also revolutionised the production of the Rolls Royce RB211 fan blade blanks and turned around a number of local aerospace and automotive businesses before starting up Hartech.
It will therefore not come as a surprise that despite having no previous motor racing experience - when we entered motor racing in the Porsche Club Championship we didn't buy success by sourcing a winning car but built our own from scratch and had a win at our first ever meeting and despite pulling out two years ago our cars still hold the lap records at all the circuits. Furthermore - to counter suspicion that our engines were illegal I arranged for them to be sealed and at the end of the season - stripped - thoroughly inspected and declared totally standard.
All this achieved with a team of 3 or 4 people while earning a living doing something else and with limited funding that in comparison to the likes of those who we beat (most of the Japanese motorcycle industry) and up against motor racing teams with years of experience - is something to be proud of.
So - yes not claiming to be anything like as capable or experienced as Porsche - but also not a bunch of amateurs and deserving of more respect than that trotted out above! (Short video @ www.hartech.org demonstrates much of the above).
Baz (embarrassed and self conscious at posting this but annoyed at the disrespect posted) - sorry! please forgive this lapse of modesty.
BOOM!Despite the sarcasm we do not of course remotely suggest we know more than Porsche nor could have designed or run cars to win the Championships that they did (for which some rather obvious financial differences impact), however manufacturers design and build to a price and a market and try new technology where they believe it will make the product better or their own margins larger.
Porsche knew how to make closed deck engines with Nikasil alloy liners (GT3 and Turbo's) - but charged much more for them and tried Lokasil in the less expensive N/A Boxster, Cayman, 996 and 997 examples. They almost got away with it (as most are still reliable and especially with the smaller capacity variants) but suffered greater failure rates than the public (or them I suspect) would have anticipated - so reverted to another previously successful technology for the Gen 2 engines (almost certainly costing them a little more and reducing margins).
We simply recognised the weaknesses early on and invested in making our repair system efficient and applied the same technology as Porsche already used in the GT3 and turbo's of a Nikasil alloy liner in a closed deck assembly. Not exactly rocket science just providing a higher quality proven solution and doing it in a flow production system and with new specialised machinery and highly experienced and trained staff. After initially manufacturing our own liners - as quantities increased to over a thousand/year - we also sub-contracted that manufacture to a highly respected F1 supplier with the greatest reputation.
But for the money and reorganisation we put into our top quality repairs - our solution may have become too expensive (compared to inferior alternatives) but that early effort has enabled us to supply this to the market at about the same price others charge for discredited and out of date technology resulting in us still expanding and supplying to Worldwide markets (now including North America).
So - we do not inflate our own ego's by imagining we are superior to Porsche at all - perhaps we just built the engines to the specification they could have done first time with obvious benefits.
Having said that - by way of answering sarcasm - would you over critical posters allow me to be a bit cheeky and big headed and counter that criticism by simply stating a few facts that many years ago now (1) I designed, manufactured and built a three cylinder 350 motorcycle that first time it was ever on a track - Barry Sheene tested at Brands Hatch (breaking the lap record), The 500cc Sparton engine that first time in a race was the fastest at the IOM TT and amongst numerous International wins was 1st and second in the North West 200 (Britains fastest road race) and The 750cc Phoenix 4 engine that won several TT races (and powered David Essex's Silver Dream Racer (and the whole bike) - all achieved without use of a dyno at that time. Then with a dyno to develop the engines - the 350 cc in line twin with the World's first fully carbon fibre chassis that ridden by Nial McKenzie won the British Championship twice and finished 3rd in the World Championship French GP, was responsible for the 250cc Armstrong that won a GP and designed and manufactured various upgrades for Susuki works racers, Nortons, Ducatis, Kawasakis and Hondas.
Before you are too sick of me - I also revolutionised the production of the Rolls Royce RB211 fan blade blanks and turned around a number of local aerospace and automotive businesses before starting up Hartech.
It will therefore not come as a surprise that despite having no previous motor racing experience - when we entered motor racing in the Porsche Club Championship we didn't buy success by sourcing a winning car but built our own from scratch and had a win at our first ever meeting and despite pulling out two years ago our cars still hold the lap records at all the circuits. Furthermore - to counter suspicion that our engines were illegal I arranged for them to be sealed and at the end of the season - stripped - thoroughly inspected and declared totally standard.
All this achieved with a team of 3 or 4 people while earning a living doing something else and with limited funding that in comparison to the likes of those who we beat (most of the Japanese motorcycle industry) and up against motor racing teams with years of experience - is something to be proud of.
So - yes not claiming to be anything like as capable or experienced as Porsche - but also not a bunch of amateurs and deserving of more respect than that trotted out above! (Short video @ www.hartech.org demonstrates much of the above).
Baz (embarrassed and self conscious at posting this but annoyed at the disrespect posted) - sorry! please forgive this lapse of modesty.
Where does Miller EE nanodrive fit in? it has this nanodrive stuff and looks to be Porsche A40 approved but would it be advisable (as seems from the prior hartech post) to use a thicker quality ester based oil (motul sport or non nano Miller CFS) instead over that? Or just go the whole hog and use the nano Miller CFS...? 
Love this topic always gets a few strong opinions.
Anyway I have a 997 g1 and have asked a fair few people. The question of whether to use millers seems to be more about whether you belive in nanotechnology oil, seems to make sense to me being an x aircraft engineer but each to their own assessment. However there is no question that mobile 1 is still good stuff, it's a very expensive well developed oil, but it's not nanotechnology.
I buy into Baz's explanation of bore scoring and thus believe this nanotechnology oil would help, if you don't then don't buy it, if you do then it makes sense.
Which nanotechnology oil, if it's millers then which one fully synthetic 5-40, semi 10-40, or 10-50 fully synthetic.... and here I think the general indy advice is handy, they usually put 10-40 semi synthetic in cars with 70+k miles as they say the thinner oils would burn a bit more due to engine wear, I personally use 5-40w fully synthetic but if I had experienced excessive oil use then I would have used 10-40w semi-synthetic.
Not really sure where 10-50w synthetic come in but I guess it's just thicker synthetic stuff. Do I notice a difference with millers oil? Well I think it would be very very difficult to notice so I'm it sure but makes me feel happier and it's not that expensive on eBay.
Anyway I have a 997 g1 and have asked a fair few people. The question of whether to use millers seems to be more about whether you belive in nanotechnology oil, seems to make sense to me being an x aircraft engineer but each to their own assessment. However there is no question that mobile 1 is still good stuff, it's a very expensive well developed oil, but it's not nanotechnology.
I buy into Baz's explanation of bore scoring and thus believe this nanotechnology oil would help, if you don't then don't buy it, if you do then it makes sense.
Which nanotechnology oil, if it's millers then which one fully synthetic 5-40, semi 10-40, or 10-50 fully synthetic.... and here I think the general indy advice is handy, they usually put 10-40 semi synthetic in cars with 70+k miles as they say the thinner oils would burn a bit more due to engine wear, I personally use 5-40w fully synthetic but if I had experienced excessive oil use then I would have used 10-40w semi-synthetic.
Not really sure where 10-50w synthetic come in but I guess it's just thicker synthetic stuff. Do I notice a difference with millers oil? Well I think it would be very very difficult to notice so I'm it sure but makes me feel happier and it's not that expensive on eBay.
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