997 cylinder liners
Discussion
Later today I will be posting some figures to support my position.
Meanwhile can I respond by saying that placing blame is something different people in different positions will disagree on and not something I need to comment on - all I do is present my findings combined with my experiences and thoughts for others to make up their own minds on who to blame and how much. I do advise people that litigation is a bad choice unlikly to provide any kind of answer and that a more pragmatic approach is best by simply accepting the situation and finding a suitable solution.
It is IMHO irrelevant that our mods may invalidate a Porsche warranty. Our only customers are owners who don't have one and/or don't want another engine made without the modifications we supply to eliminate or reduce the potential weak spots and cannot afford or justify the cost of a new engine for an older and less valuable car
Furthmore although we have always advised the benefit of a Porsche warranty (if you can afford it) as the cars age and values reduce we offer a less expensive alternative and after the tenth year - the only alternative (because ours last the Lifetime of the car if the customer continues with it).
I don't regard it as pendantic semantics to clear up a good description of the fault. It is possible for a cylinder to be scored by poor l ubrication or a foreign body, or for it to be honed back to normality and for the piston to still be unmarked or useable. Saying "your cylinders are scored" implies that you could still drive the car satisfactorily - and minimises the severity of the problem and cause - IMHO. Furthermore - to call it "cylinder scoring" - when the piston is completely wrecked and has rubbed so hard into the cylinder bore - it deposited aluminium and marked the cylinder wall - is to take that to a level that misinforms the owner. You cannot see the damage to the piston when inspecting the bore with a camera - so just informing owners that they have some cylinder scoring when they will also have a totally wrecked piston hidng inside and out of sight - is - for my money - a gross example of mis-information.
To be pedantic - if you "seize something" you don't need to stop it moving. You can seize a rope and slow it down but not stop it. If it was a single cylinder engine this type of damage would slow the engine and the owner would feel it. Because it has 5 other cylinders and because temperature rises over 3-4 seconds cause the damage after which the piston is smaller and imediately fits the hole again and never seizes again - it is usually not felt or experienced. The damage is only caused by the surface temperature of the piston being so high that the lubricant can no longer allow it to slide in the bore and the metal to Lokasil contact takes place sufficiently hard to scrub deep grooves into the piston face and often trap the oil control and compression rings - a lot more serious than "cylinder scoring" IMHO which is just a visible consequence of a more serious problem.
However we all have different opinions on the right way to describe something and so if you prefer "picking up" please read my "seized" in that way (and I did at least describe exactly what I meant by it - so does it really matter?).
I agree that many high performance engines have problems and weak spots and anyway the Porsche 996 and 997 models are excellent sports cars with fantastic overall reliability and a very small number of failures.
With various different warranty options available - owners can enjoy driving a brilliant car and cover themselves against the very rare likelyhood of an expensive failure.
However - for those unfortunate owners who do not have any warranty (or reliable cover) it is a major problem and because I understand that problem and can offer more affordable (and arguably better) solutions - and explain the root causes - I hope it is valued by them that they can avoid being brushed off with inaccurate information and know more about the situation - whatever they decide to do about it.
Baz
Meanwhile can I respond by saying that placing blame is something different people in different positions will disagree on and not something I need to comment on - all I do is present my findings combined with my experiences and thoughts for others to make up their own minds on who to blame and how much. I do advise people that litigation is a bad choice unlikly to provide any kind of answer and that a more pragmatic approach is best by simply accepting the situation and finding a suitable solution.
It is IMHO irrelevant that our mods may invalidate a Porsche warranty. Our only customers are owners who don't have one and/or don't want another engine made without the modifications we supply to eliminate or reduce the potential weak spots and cannot afford or justify the cost of a new engine for an older and less valuable car
Furthmore although we have always advised the benefit of a Porsche warranty (if you can afford it) as the cars age and values reduce we offer a less expensive alternative and after the tenth year - the only alternative (because ours last the Lifetime of the car if the customer continues with it).
I don't regard it as pendantic semantics to clear up a good description of the fault. It is possible for a cylinder to be scored by poor l ubrication or a foreign body, or for it to be honed back to normality and for the piston to still be unmarked or useable. Saying "your cylinders are scored" implies that you could still drive the car satisfactorily - and minimises the severity of the problem and cause - IMHO. Furthermore - to call it "cylinder scoring" - when the piston is completely wrecked and has rubbed so hard into the cylinder bore - it deposited aluminium and marked the cylinder wall - is to take that to a level that misinforms the owner. You cannot see the damage to the piston when inspecting the bore with a camera - so just informing owners that they have some cylinder scoring when they will also have a totally wrecked piston hidng inside and out of sight - is - for my money - a gross example of mis-information.
To be pedantic - if you "seize something" you don't need to stop it moving. You can seize a rope and slow it down but not stop it. If it was a single cylinder engine this type of damage would slow the engine and the owner would feel it. Because it has 5 other cylinders and because temperature rises over 3-4 seconds cause the damage after which the piston is smaller and imediately fits the hole again and never seizes again - it is usually not felt or experienced. The damage is only caused by the surface temperature of the piston being so high that the lubricant can no longer allow it to slide in the bore and the metal to Lokasil contact takes place sufficiently hard to scrub deep grooves into the piston face and often trap the oil control and compression rings - a lot more serious than "cylinder scoring" IMHO which is just a visible consequence of a more serious problem.
However we all have different opinions on the right way to describe something and so if you prefer "picking up" please read my "seized" in that way (and I did at least describe exactly what I meant by it - so does it really matter?).
I agree that many high performance engines have problems and weak spots and anyway the Porsche 996 and 997 models are excellent sports cars with fantastic overall reliability and a very small number of failures.
With various different warranty options available - owners can enjoy driving a brilliant car and cover themselves against the very rare likelyhood of an expensive failure.
However - for those unfortunate owners who do not have any warranty (or reliable cover) it is a major problem and because I understand that problem and can offer more affordable (and arguably better) solutions - and explain the root causes - I hope it is valued by them that they can avoid being brushed off with inaccurate information and know more about the situation - whatever they decide to do about it.
Baz
“Does anyone know why cylinder 6 is frequently scoring on the 997 3.6 engines” was asked on the Internet many months ago and since we have repaired increasing numbers with that very problem and written at length on the subject to discuss the causes and solutions.
I had hoped to wait until actual temperature tests were completed to finalise our conclusions but with so much correspondence going on since - have decided to reveal the theoretical explanation first.
Traditionally engines were designed so that all the coolant went into one part of the cylinder block and passed through it and into the cylinder head before going to the radiator. The greatest cooling is achieved by the coolest coolant – so as it heated up on it’s way through the engine – it was progressively less able to remove heat and the cylinders all ran at slightly different temperatures with the head receiving the warmed up coolant last and therefore being the hottest. The cylinders have to do a difficult job of keeping the piston face sufficiently cool to allow the oil to stop the piston seizing (or “picking up”) made worse as power increases and were traditionally cooled by 100% of the coolant first. The cylinder head (valves, camshafts etc) have a much easier life because how much power the cylinder is making makes little difference to how they work reliably (unless cavitation occurs through just running to hot).
Because the cylinders used to run so cool – these temperature differences were usually no problem unless the output was significantly increased and tuners frequently often found that after turbo or super charging standard engines – they had to alter the coolant flow proportions to balance those temperatures and avoid hot spots that limited reliability.
More recently engines have become more sophisticated and exploited the extra surface area in the cylinder jacket by reducing the flow or coolant depth in there, increasing it to the cylinder head and even flowing the coolant through a header pipe to individual cylinders - changing the amount in each cylinder and head to get a better balance – driven on partially by the increase in cylinder temperatures resulting form reduced emission regulations to avoid detonation.
The M96 Boxster and 996 engines up to 3.4 litres were typical of a newer regime with coolant flow controlled by different hole sizes in the cylinder casting and head gaskets. Because the cylinder heads are fitted opposite ways round on each side of the engine (the front on one side being the back on the other side) the gaskets had to be “handed” for each bank with different sized holes feeding different cylinders. It meant that if cylinder head gaskets were fitted to the wrong side it would reverse that balance and make the least coolant go to the hottest cylinder – but as long as they were fitted correctly the engine seemed well balanced thermally.
With the coolant pump being on the bank 1 side (cylinders 1, 2 and 3) feeding straight into cylinder 1 and bank 2 (cylinders 4, 5 and 6 which unlike bank 1 also have the piston thrust face on the hotter side – a longer coolant channel and an oil cooler) being some distance away - you would have expected the least coolant flow to bank 1 and cylinder 1 and the most flow to bank 2 and especially cylinder 6.
This is exactly what we found. Using the area of each feed hole as an approximation of the coolant flow proportions - the % of the total coolant in each cylinder of a 996 3.4 was as follows (cylinder sequence 1-6) 3%, 3%, 3%, 2.7%, 3%, 4% and each head as follows 8.9%, 11.3%, 15%, 8%, 11%, 27%. Overall head and cylinder combined the result is 12%, 14.4%, 18%, 10.7%, 14.3% 30.6% and although personally – overall - I would like to see a greater proportion of the coolant in the cylinders (and less in the heads) - no particular seizing (or “picking up”) problems emerged unless some other fault occurred like cracked liners or heads or coolant failures.
Changes to this system were found in the 996 and 997 3.6 and 3.8 engines. The size of the holes in cylinder block (feeding each cylinder) were altered slightly and the holes in the head gasket were made the same size for all cylinders (and the gasket could therefore now be fitted to either bank). With these engines producing more power and more thrust on the piston face I would have expected the proportions of the coolant going to the cylinders to be increased – but instead the size of the holes in the cylinder head gasket were made bigger – increasing the % flow to the head and reducing it to the cylinders – which will therefore run hotter with cylinder 6 being the most vulnerable.
The result is that now the % of coolant in each cylinder is as follows (3.6 cylinder sequence 1-6) 1.65%, 1.63%, 1.61%, 1.64%, 1.89%, 2.43% and in each head is as follows , 14.9%, 14.9%, 14.9%, 14.9%, 14.9%, 14.9% and the combined result in each cylinder is 16.5%, 16.5%, 16.5%, 16.5%, 16.75%, 17.29%.
Bank 2 now receives 9% less coolant than it did before and cylinder 6 (the one likely to potentially run the hottest) now receives the least % of coolant and overall receives 40% less than it did before in the 3.4 engine.
The 3.8 is similar but has 45% less coolant in the number 6 cylinder than a 996 3.4 and has 44% proportionally less coolant flow in the cylinders. I didn’t check the flow areas in the Cayman S we recently rebuilt but I think it will prove to be the same and I will check next time.
I could of course be entirely wrong about all this and it could be that adding more coolant to the cylinder heads overall makes the engine run cooler and there is some other explanation for the failures. However whenever in the last 45 years I have come across an engine engineering problem and the evidence points in the same direction as the technical analysis – it has always proven to be right.
To review it in very simple terms – engines used to have 100% of the coolant passing into the blocks first and these engines have reduced that to about 10% of the total (3.8), 8.5% (3.6) and 15% (3.4 996) as the engines have increased in power output and torque – at the same time as this balance of the amount of coolant passing through the block and cooling the pistons has reduced - some pistons are seizing (or if you prefer “picking up”) on the thrust face on the side worse effected by the changes and in the greatest need of cooler cylinders.
It seems to me that either some gaskets were found to have been fitted the wrong way round (and this change was thought to be a solution to that) – or the engineers went in entirely the wrong direction when altering the design (which I find unlikely) or accountants over-ruled engineers for the miniscule benefits of cost reduction through one standard rather than two head gaskets being used.
Whatever the reasoning, economics or politics – there is no doubt to me that the increased incidence of cylinder to piston face failures that causes cylinder scoring/piston seizing (or “picking up”) – is directly related to the these technical and logistical alterations – pushing the cylinder temperatures on all cylinders higher and bank two and cylinder 6 in particular.
There are not many options available to correct this. We can at present only alter the areas feeding individual cylinders during a full strip and rebuild. New, handed, head gaskets with different feed-hole sizes to each cylinder could also improve the balance and coolant volumes (cylinders to cylinder and cylinders to heads) but would require a lot of work to change as a preventative measure and since there is a small change in the hole position of one bolt – the older 3.4 gaskets cannot easily be used for the 3.6 (same bore) and modified ones are not available.
A lower running temperature thermostat – would be the least expensive option – because despite not altering the overall balance – it would at least reduce the actual cylinder wall temperatures of all the cylinders - and will be available from us soon.
Unfortunately – for us to prove the above analysis and test out the results of all these options by fitting temperature sensors to different parts of different engines and compiling the results – is a major undertaking (which is in progress) but IMHO the need for something to be done (and for owners to be more informed) is taking precedence over awaiting that confirmation and the above evidence is so compelling that I feel it serves a useful purpose to reveal and explain it all now.
My only purpose in doing this is to empower owners who may have been mislead, explain that improvements are undertaken @ Hartech when rebuilding engines, that a low cost improvement will shortly be available from us and that full actual test results will follow to hopefully verify this analysis. My reason for conveying all this now before those results are available is just because they will still unfortunately be a long way off completion.
Baz
I had hoped to wait until actual temperature tests were completed to finalise our conclusions but with so much correspondence going on since - have decided to reveal the theoretical explanation first.
Traditionally engines were designed so that all the coolant went into one part of the cylinder block and passed through it and into the cylinder head before going to the radiator. The greatest cooling is achieved by the coolest coolant – so as it heated up on it’s way through the engine – it was progressively less able to remove heat and the cylinders all ran at slightly different temperatures with the head receiving the warmed up coolant last and therefore being the hottest. The cylinders have to do a difficult job of keeping the piston face sufficiently cool to allow the oil to stop the piston seizing (or “picking up”) made worse as power increases and were traditionally cooled by 100% of the coolant first. The cylinder head (valves, camshafts etc) have a much easier life because how much power the cylinder is making makes little difference to how they work reliably (unless cavitation occurs through just running to hot).
Because the cylinders used to run so cool – these temperature differences were usually no problem unless the output was significantly increased and tuners frequently often found that after turbo or super charging standard engines – they had to alter the coolant flow proportions to balance those temperatures and avoid hot spots that limited reliability.
More recently engines have become more sophisticated and exploited the extra surface area in the cylinder jacket by reducing the flow or coolant depth in there, increasing it to the cylinder head and even flowing the coolant through a header pipe to individual cylinders - changing the amount in each cylinder and head to get a better balance – driven on partially by the increase in cylinder temperatures resulting form reduced emission regulations to avoid detonation.
The M96 Boxster and 996 engines up to 3.4 litres were typical of a newer regime with coolant flow controlled by different hole sizes in the cylinder casting and head gaskets. Because the cylinder heads are fitted opposite ways round on each side of the engine (the front on one side being the back on the other side) the gaskets had to be “handed” for each bank with different sized holes feeding different cylinders. It meant that if cylinder head gaskets were fitted to the wrong side it would reverse that balance and make the least coolant go to the hottest cylinder – but as long as they were fitted correctly the engine seemed well balanced thermally.
With the coolant pump being on the bank 1 side (cylinders 1, 2 and 3) feeding straight into cylinder 1 and bank 2 (cylinders 4, 5 and 6 which unlike bank 1 also have the piston thrust face on the hotter side – a longer coolant channel and an oil cooler) being some distance away - you would have expected the least coolant flow to bank 1 and cylinder 1 and the most flow to bank 2 and especially cylinder 6.
This is exactly what we found. Using the area of each feed hole as an approximation of the coolant flow proportions - the % of the total coolant in each cylinder of a 996 3.4 was as follows (cylinder sequence 1-6) 3%, 3%, 3%, 2.7%, 3%, 4% and each head as follows 8.9%, 11.3%, 15%, 8%, 11%, 27%. Overall head and cylinder combined the result is 12%, 14.4%, 18%, 10.7%, 14.3% 30.6% and although personally – overall - I would like to see a greater proportion of the coolant in the cylinders (and less in the heads) - no particular seizing (or “picking up”) problems emerged unless some other fault occurred like cracked liners or heads or coolant failures.
Changes to this system were found in the 996 and 997 3.6 and 3.8 engines. The size of the holes in cylinder block (feeding each cylinder) were altered slightly and the holes in the head gasket were made the same size for all cylinders (and the gasket could therefore now be fitted to either bank). With these engines producing more power and more thrust on the piston face I would have expected the proportions of the coolant going to the cylinders to be increased – but instead the size of the holes in the cylinder head gasket were made bigger – increasing the % flow to the head and reducing it to the cylinders – which will therefore run hotter with cylinder 6 being the most vulnerable.
The result is that now the % of coolant in each cylinder is as follows (3.6 cylinder sequence 1-6) 1.65%, 1.63%, 1.61%, 1.64%, 1.89%, 2.43% and in each head is as follows , 14.9%, 14.9%, 14.9%, 14.9%, 14.9%, 14.9% and the combined result in each cylinder is 16.5%, 16.5%, 16.5%, 16.5%, 16.75%, 17.29%.
Bank 2 now receives 9% less coolant than it did before and cylinder 6 (the one likely to potentially run the hottest) now receives the least % of coolant and overall receives 40% less than it did before in the 3.4 engine.
The 3.8 is similar but has 45% less coolant in the number 6 cylinder than a 996 3.4 and has 44% proportionally less coolant flow in the cylinders. I didn’t check the flow areas in the Cayman S we recently rebuilt but I think it will prove to be the same and I will check next time.
I could of course be entirely wrong about all this and it could be that adding more coolant to the cylinder heads overall makes the engine run cooler and there is some other explanation for the failures. However whenever in the last 45 years I have come across an engine engineering problem and the evidence points in the same direction as the technical analysis – it has always proven to be right.
To review it in very simple terms – engines used to have 100% of the coolant passing into the blocks first and these engines have reduced that to about 10% of the total (3.8), 8.5% (3.6) and 15% (3.4 996) as the engines have increased in power output and torque – at the same time as this balance of the amount of coolant passing through the block and cooling the pistons has reduced - some pistons are seizing (or if you prefer “picking up”) on the thrust face on the side worse effected by the changes and in the greatest need of cooler cylinders.
It seems to me that either some gaskets were found to have been fitted the wrong way round (and this change was thought to be a solution to that) – or the engineers went in entirely the wrong direction when altering the design (which I find unlikely) or accountants over-ruled engineers for the miniscule benefits of cost reduction through one standard rather than two head gaskets being used.
Whatever the reasoning, economics or politics – there is no doubt to me that the increased incidence of cylinder to piston face failures that causes cylinder scoring/piston seizing (or “picking up”) – is directly related to the these technical and logistical alterations – pushing the cylinder temperatures on all cylinders higher and bank two and cylinder 6 in particular.
There are not many options available to correct this. We can at present only alter the areas feeding individual cylinders during a full strip and rebuild. New, handed, head gaskets with different feed-hole sizes to each cylinder could also improve the balance and coolant volumes (cylinders to cylinder and cylinders to heads) but would require a lot of work to change as a preventative measure and since there is a small change in the hole position of one bolt – the older 3.4 gaskets cannot easily be used for the 3.6 (same bore) and modified ones are not available.
A lower running temperature thermostat – would be the least expensive option – because despite not altering the overall balance – it would at least reduce the actual cylinder wall temperatures of all the cylinders - and will be available from us soon.
Unfortunately – for us to prove the above analysis and test out the results of all these options by fitting temperature sensors to different parts of different engines and compiling the results – is a major undertaking (which is in progress) but IMHO the need for something to be done (and for owners to be more informed) is taking precedence over awaiting that confirmation and the above evidence is so compelling that I feel it serves a useful purpose to reveal and explain it all now.
My only purpose in doing this is to empower owners who may have been mislead, explain that improvements are undertaken @ Hartech when rebuilding engines, that a low cost improvement will shortly be available from us and that full actual test results will follow to hopefully verify this analysis. My reason for conveying all this now before those results are available is just because they will still unfortunately be a long way off completion.
Baz
after a rocky start this has turned in to an interesting post reminds me of the heat seizures of my 2 stroke motorcycle days,then you use to pull the clutch in coast to a stop and wait for the engine to cool.firstly excuse my mechanical/engineering ignorance i am neither.if these are indeeded heat seizures due to poor coolant flow would this not infact affect every single car and not small percentage or is it down to the driving conditions when this occures ie lots of slow town use?
a couple of questions that might seem a be a bit dumb but during the manufacturer of blocks/heads could some have slightly narrower coolant channels when cast?also does the lockasil liner dissipate heat less effectively than other materials?
finally could be something to do with the oil?i found thiswww.lnengineering.com/oil.html
a couple of questions that might seem a be a bit dumb but during the manufacturer of blocks/heads could some have slightly narrower coolant channels when cast?also does the lockasil liner dissipate heat less effectively than other materials?
finally could be something to do with the oil?i found thiswww.lnengineering.com/oil.html
Edited by mayes911 on Tuesday 12th October 20:44
mayes911 said:
reminds me of the heat seizures of my 2 stroke motorcycle days,then you use to pull the clutch in coast to a stop
Aha! I was thinking about that as I read Baz' post, on my Lambretta's I often found with the 200cc cylinders that the exhaust side of the piston got too hot and the surface picked up, a bit of wet and dry to clean it up and we were off again, I ran 10% methanol for a while as it burns cooler, then in the mid to late 80's a cylinder came along that was cast in aluminium with a nicasil bore, bloody marvellous it was, joint effort with a fella called Terry Shepard and AF Rayspeed. It was a giant leap.Its a great pity the 997 engines are suffering, hopefully it wont turn out to be too epidemic as time goes on. Painful for those that suffer.
As usual Baz, a very interesting and well presented read - thanks for taking the time to share it.
i too had a lambretta in the early 80s af250.my friend is still in to his lambrettas he has af225(the one you mentioned from the late 80s) which is much more advanced these days (ceramic bores, 8 petal reed valves,flat slide carbs)he had his race tuned which was more like the perfomance of a motorcrosser but sadly it twisted cranks so he is back with the standard af kit
Edited by mayes911 on Tuesday 12th October 21:26
A few answers needed.
I have not got the facilites to test the difference in heat transfer rates but air pockets are used as a thermal insulator in most applications and the Lokasil is a good cylinder material because it has very high porosty (70% or so I believe) which must also be air or gas pockets or filled with oil - neither of which will be a good heat transfer material - so YES I think the surface of the material will run hotter than Nikasil - but only from the above logic - not proven.
The question - why does every one not fail applies to ever failure ever experienced anywhere in the World from cars and motorcycles to planes and TV's etc and has something to do with random failure and catastrophe theory - but whenever a product or part is manufactured closer to the usual satisfactory limit - a few random examples start to fail in small numbers and the nearer the product or part is to that limit the higher the incidences.
GT and turbo engines and cars cost a lot more and have higher cylinder bore to piston pressures and Porsche decided in their wisdom to use Nikasil for this application - more expensive but probably better. Lokasil is cheaper and fitted to less powerful examples.
This is all part of my conclusion that the evidence is that as the engines have been producing more power and torque and increasing the piston to cylinder wall pressures - but in a casing with the same basic cooling but less of it being directed through the cylinders - more failures have occured.
The castings are not different (very good quality actually) and anyway the flow is controlled by the thermostat.
In my view oil @ 0-40 is too thin as engines wear and increase clearances and temperatures (but I cannot back this up with anything other than experience - sorry and am not getting into any arguments about it). We use a semi-synthetic 10-40 because we think it is more suitable.
Engine oil and coolant deteriorate with age and the inside of the engine castings gradually gets a coating that slightly reduces heat transfer capability. In my view both eengine oil and coolant should be changed more frequently - but lowering the overal running temperature both increases heat transfer and oil viscosity and IMHO is a good compromise solution. The extended oil change intervals are in IMHO a mistake.
I looked up the LN engineering print outs (as suggested) and they were not only very interesting but almost a mirror image of our own publications and buyers guide information and photographs in the section 4 (www.hartech.org). I am too modest to say "great minds think alike" but they do seem to be doing all the right things (or amazingly similar things) in the USA as we are in the UK.
Well that answers everything up to date I think - I will try and post some photos soon to demonstrate how big the problem is becoming.
Baz
I have not got the facilites to test the difference in heat transfer rates but air pockets are used as a thermal insulator in most applications and the Lokasil is a good cylinder material because it has very high porosty (70% or so I believe) which must also be air or gas pockets or filled with oil - neither of which will be a good heat transfer material - so YES I think the surface of the material will run hotter than Nikasil - but only from the above logic - not proven.
The question - why does every one not fail applies to ever failure ever experienced anywhere in the World from cars and motorcycles to planes and TV's etc and has something to do with random failure and catastrophe theory - but whenever a product or part is manufactured closer to the usual satisfactory limit - a few random examples start to fail in small numbers and the nearer the product or part is to that limit the higher the incidences.
GT and turbo engines and cars cost a lot more and have higher cylinder bore to piston pressures and Porsche decided in their wisdom to use Nikasil for this application - more expensive but probably better. Lokasil is cheaper and fitted to less powerful examples.
This is all part of my conclusion that the evidence is that as the engines have been producing more power and torque and increasing the piston to cylinder wall pressures - but in a casing with the same basic cooling but less of it being directed through the cylinders - more failures have occured.
The castings are not different (very good quality actually) and anyway the flow is controlled by the thermostat.
In my view oil @ 0-40 is too thin as engines wear and increase clearances and temperatures (but I cannot back this up with anything other than experience - sorry and am not getting into any arguments about it). We use a semi-synthetic 10-40 because we think it is more suitable.
Engine oil and coolant deteriorate with age and the inside of the engine castings gradually gets a coating that slightly reduces heat transfer capability. In my view both eengine oil and coolant should be changed more frequently - but lowering the overal running temperature both increases heat transfer and oil viscosity and IMHO is a good compromise solution. The extended oil change intervals are in IMHO a mistake.
I looked up the LN engineering print outs (as suggested) and they were not only very interesting but almost a mirror image of our own publications and buyers guide information and photographs in the section 4 (www.hartech.org). I am too modest to say "great minds think alike" but they do seem to be doing all the right things (or amazingly similar things) in the USA as we are in the UK.
Well that answers everything up to date I think - I will try and post some photos soon to demonstrate how big the problem is becoming.
Baz
hartech said:
Loads of common sense...
LOL! I have always disliked 0w-40. It feels like pouring water into your car instead of oil. I was going to mention this earlier but figured people here had discussed it before and I was going to make a fool of myself. TVR used to recommend this oil for their own v8 and I used it for a while but the endurance race team I use to look after my car recommended..... 10w-40 semi synthetic!!I wasn't convinced at first but oil consumption dropped, pressure was higher at hot idle and I am generally much happier. I was initially worried about 'semi' synthetic oil as it doesn't sound as good as 'fully' synthetic. However their view was 'it works fine in our race cars for 24 hours, but for peace of mind simply change it more frequently.'
The problem is that if your car is in warranty it will have to run on 0w-40 for the first few years of its life so by the time you might think of switching the oil the damage may already be done...
ro_butler said:
hartech said:
Loads of common sense...
LOL! I have always disliked 0w-40. It feels like pouring water into your car instead of oil. I was going to mention this earlier but figured people here had discussed it before and I was going to make a fool of myself. TVR used to recommend this oil for their own v8 and I used it for a while but the endurance race team I use to look after my car recommended..... 10w-40 semi synthetic!!I wasn't convinced at first but oil consumption dropped, pressure was higher at hot idle and I am generally much happier. I was initially worried about 'semi' synthetic oil as it doesn't sound as good as 'fully' synthetic. However their view was 'it works fine in our race cars for 24 hours, but for peace of mind simply change it more frequently.'
The problem is that if your car is in warranty it will have to run on 0w-40 for the first few years of its life so by the time you might think of switching the oil the damage may already be done...
Surely if you want a 'thicker' oil at running temperature that still doesn't thicken any more than a 0W-40 when cold, then a 0W-50 is the correct oil to use?
I am not tribolgy expert and will not get drawn into arguments about oil - but the idea that oil thickens up when it gets hot is in my experience wrong. I think the claim is that it works as well as higher grade oil when hot - but this doesn't take into account that when bearings wear the lateral clearance is greater so the oil has less resistance to squeezing out the side of shells etc and therefore does not support the bearings as well. Similarly if the oil is a thicker grade it usually is thicker when hot and I have had my amateur ideas discussed with technical oil racing experts from Mobil and Castrol and both agree with my general view.
However this is one of those subjects that runs and runs and no one wins. I can say that for many years I have received phone calls from worried owners with one or more of the following symptoms - higher oil consumption, lower oil pressure and more smoking and noisier engines. I always ask if they have changed anything when the problem emerged - usually to find the reply is - "well only the oil for Mobil 1 - but then that must be OK because it is so expensive and recommended" etc etc.
When persuaded to replace it with 10-40 or sometimes 15-50 semi-synthetic I later get a grateful thanks for solving it as the engines return to normal.
Mobil is a great oil but very expensive and they make a racing version that is thicker which is a great oil (and recommended in arduous situations).
Please use whatever you want - I don't want to respond to this issue again.
Baz
However this is one of those subjects that runs and runs and no one wins. I can say that for many years I have received phone calls from worried owners with one or more of the following symptoms - higher oil consumption, lower oil pressure and more smoking and noisier engines. I always ask if they have changed anything when the problem emerged - usually to find the reply is - "well only the oil for Mobil 1 - but then that must be OK because it is so expensive and recommended" etc etc.
When persuaded to replace it with 10-40 or sometimes 15-50 semi-synthetic I later get a grateful thanks for solving it as the engines return to normal.
Mobil is a great oil but very expensive and they make a racing version that is thicker which is a great oil (and recommended in arduous situations).
Please use whatever you want - I don't want to respond to this issue again.
Baz
Akajak said:
bcnrml said:
They also warn you to run the car in for x miles (1k or 1.5k, I think). Do Porsche offer either of those? Rhetorical question, most of you know the answers to that. 
Porsche handbook clearly states running in procedure, but agreed no warning light.
Said manual having been contradicted repeatedly by a certain London OPC despite my suggesting it wouldn't be a good thing for the cars. They said that to me, repeatedly, despite my gently challenging them. How many times might that have been said to others?
On this forum, we have some people still saying the cars don't need running in! And to date, IIRC, not one OPC representative (reading this forum as they do) has come on here to suggest otherwise. If they have, please correct me (they know who they are).
Engines, gearboxes and some differentials need gentle treatment when new/young. They all need gentle treatment when cold. Ten minutes (as some continue to argue) is not long enough to warm up an engine in the UK's climate. If your manufacturer helps you make the most of the car by guiding you in real time on such matters, then they care a lot more about mechanical longevity than do those who omit such indicators.
Again, I say to people, do your research and don't be fooled by the hype. I suspect you'll find that there is only one German marque out there with a reputation for major engine issues (at surprisiegly low mileages), and that reputation now stretches over one decade and across multiple engine variants (M96, M97 and now the DFi). For the latter, look up Ian_UK1's helpful alert to carbon deposits on DFi engines. The last one presents new problems even I optimistically hoped wouldn't be there or cost much to rectify. But hey, when you sign up to the ownership experience, you'd better be sure to cover the subscription costs because they are not anything like as low as some would have you believe!
hartech said:
I am not tribolgy expert and will not get drawn into arguments about oil - but the idea that oil thickens up when it gets hot is in my experience wrong. I think the claim is that it works as well as higher grade oil when hot - but this doesn't take into account that when bearings wear the lateral clearance is greater so the oil has less resistance to squeezing out the side of shells etc and therefore does not support the bearings as well. Similarly if the oil is a thicker grade it usually is thicker when hot and I have had my amateur ideas discussed with technical oil racing experts from Mobil and Castrol and both agree with my general view.
However this is one of those subjects that runs and runs and no one wins. I can say that for many years I have received phone calls from worried owners with one or more of the following symptoms - higher oil consumption, lower oil pressure and more smoking and noisier engines. I always ask if they have changed anything when the problem emerged - usually to find the reply is - "well only the oil for Mobil 1 - but then that must be OK because it is so expensive and recommended" etc etc.
When persuaded to replace it with 10-40 or sometimes 15-50 semi-synthetic I later get a grateful thanks for solving it as the engines return to normal.
Mobil is a great oil but very expensive and they make a racing version that is thicker which is a great oil (and recommended in arduous situations).
Please use whatever you want - I don't want to respond to this issue again.
Baz
Of course oil doesn't thicken as it gets hot. The grades simply indicate the viscosity of the oil both when cold and when hot, based on SAE viscosity standards.However this is one of those subjects that runs and runs and no one wins. I can say that for many years I have received phone calls from worried owners with one or more of the following symptoms - higher oil consumption, lower oil pressure and more smoking and noisier engines. I always ask if they have changed anything when the problem emerged - usually to find the reply is - "well only the oil for Mobil 1 - but then that must be OK because it is so expensive and recommended" etc etc.
When persuaded to replace it with 10-40 or sometimes 15-50 semi-synthetic I later get a grateful thanks for solving it as the engines return to normal.
Mobil is a great oil but very expensive and they make a racing version that is thicker which is a great oil (and recommended in arduous situations).
Please use whatever you want - I don't want to respond to this issue again.
Baz
A 0-40 will be less viscous than a 5-40 when cold. They will have equal viscosity when hot, which is when it really matters in terms of holding pressure and perhaps not burning it.
DSM2 said:
A 0-40 will be less viscous than a 5-40 when cold. They will have equal viscosity when hot, which is when it really matters in terms of holding pressure and perhaps not burning it.
That's the theory. Didn't seem to pan out that way for me. If I change to 0w-40 my oil consumption increases and oil pressure at hot idle is lower..... (suggesting to me lower viscosity). The shear strength may not be compromised but that is impossible for me to check.Gassing Station | Porsche General | Top of Page | What's New | My Stuff