what oil in a race rover v8
Discussion
www.silkoleneoil.com/techtip6.htm
www.mpt.org/motorweek/goss/2313.shtml
The trend is to Owt for Qualy
Theory does not always work in practice!
Three Exxon Researchers found that a minimum HTHS of about 2.8 mPA.s was the minimum HTHS viscosity needed for normal wear, with the higher the HTHS being better for minimum wear. Porsche specify a minimum of 3.6.
www.mpt.org/motorweek/goss/2313.shtml
The trend is to Owt for Qualy
Theory does not always work in practice!
Three Exxon Researchers found that a minimum HTHS of about 2.8 mPA.s was the minimum HTHS viscosity needed for normal wear, with the higher the HTHS being better for minimum wear. Porsche specify a minimum of 3.6.
v8 jago said:
Now i am a little confused in what oil to put in it ! My old engine i used valvoline racing oil which used to work well it was a 20-50 without detergent in. valvoline have stopped making that and now brought a 10-60 semi synthetic out to replace it. The only problem is real steel and other places that deal in rover v8 say dont use semi synthetic or even fully synthetic. The oil wants to be about 20-50 as rovers dont have a very good oil pressure and any less than 20 is maybe to thin. I change my oil 2 or three times over the summer time and only cover approx 1000 miles in that time.
Since when have Valvoline stopped making 20w50 racing oil?, I am able to obtain it OK
I went to a shop and that is what they told me ! Do you expect me to call them a liar and tell them that i will go elsewhere?? Im just repeating what i was told. Given more time i would look further afeild to see if i can buy some else where. I was racing the next day and needed some oil and as it was closing time i felt that i was a bit stuck. I put some valvoline 15/40 in and after my first race the oil light came on so i dropped my oil and put some streight 30 in. I have never heard of it but it does the trick. It will be getting changed very regular and wont get run in winter. Has anyone ever used streight 30. (what do you think of it).
Redline race oils are straight weight.
www.redlineoil.com/products_motoroil.asp?subcatID=15
Amsoil have an oxidative thickening problem and not keen on their additive package for road oils. IMO M1 is a better product for a PAO based oil.
www.redlineoil.com/products_motoroil.asp?subcatID=15
Amsoil have an oxidative thickening problem and not keen on their additive package for road oils. IMO M1 is a better product for a PAO based oil.
v8 jago said:
I went to a shop and that is what they told me ! Do you expect me to call them a liar and tell them that i will go elsewhere?? Im just repeating what i was told. Given more time i would look further afeild to see if i can buy some else where. I was racing the next day and needed some oil and as it was closing time i felt that i was a bit stuck. I put some valvoline 15/40 in and after my first race the oil light came on so i dropped my oil and put some streight 30 in. I have never heard of it but it does the trick. It will be getting changed very regular and wont get run in winter. Has anyone ever used streight 30. (what do you think of it).
Skewse me for even asking
I think that there are some misconceptions here that need to be corrected.
0w-40, 5w-40, 10w-40 and 15w-40 are all the same thickness (14cst) at 100degC.
Centistokes (cst) is the measure of a fluid's resistance to flow (viscosity). It is calculated in terms of the time required for a standard quantity of fluid at a certain temperature to flow through a standard orifice. The higher the value, the more viscous the fluid.
As viscosity varies with temperature, the value is meaningless unless accompanied by the temperature at which it is measured. In the case of oils, viscosity is generally reported in centistokes (cst) and usually measured at 40degC and 100degC.
So, all oils that end in 40 (sae 40) are around 14cst thickness at 100degC.
This applies to all oils that end in the same number, all oils that end in 50 (sae 50) are around 18.5cst at 100degC and all oils that end in 60 (sae 60) are around 24cst at 100degC.
With me so far?
Great!
Now, ALL oils are thicker when cold. Confused? It's true and here is a table to illustrate this.
SAE 40 (straight 40)
Temp degC.........................Viscosity (thickness)
0..........................................2579cst
20..........................................473cst
40..........................................135cst
60..........................................52.2cs t
100........................................ 14cst
120.........................................8.8cst
As you will see, there is penty of viscosity at 0degC, in fact many times more than at 100degC and this is the problem especially in cold weather, can the oil flow quick enough to protect vital engine parts at start up. Not really!
So, given that an sae 40 is 14cst at 100degC which is adequate viscosity to protect the engine, and much thicker when cold, how can a 0w oil be too thin?
Well, it can't is the truth.
The clever part (thanks to synthetics) is that thin base oils can be used so that start up viscosity (on say a 5w-40 at 0degC) is reduced to around 800cst and this obviously gives much better flow than a monograde sae 40 (2579cst as quoted above).
So, how does this happen, well as explained at the beginning, it's all about temperature, yes a thin base oil is still thicker when cold than at 100degC but the clever stuff (due to synthetics again) is that the chemists are able to build these oils out of molecules that do not thin to less than 14cst at 100degC!
What are the parameters for our recommendations?
Well, we always talk about good cold start protection, by this we mean flow so a 5w will flow better than a 10w and so on. This is why we recommend 5w or 10w as the thickest you want to use except in exceptional circumstances. Flow is critical to protect the engine from wear!
We also talk about oil temps, mods and what the car is used for. This is related to the second number xw-(XX) as there may be issues with oil temperatures causing the oil to be too thin and therefore the possibility of metal to metal contact.
This is difficult to explain but, if for example your oil temp does not exceed 120degC at any time then a good "shear stable" sae 40 is perfectly capable of giving protection.
"Shear stability" is important here because if the oil shears it thins and that's not good!
However, if you are seeing temperatures in excess of 120degC due to mods and track use etc then there is a strong argument to using an sae 50 as it will have more viscosity at these excessive temperatures.
There are trade offs here. Thicker oils cause more friction and therefore more heat and they waste power and affect fuel consumption so it's always best to use the thinnest oil (i.e. second number) that you can get away with and still maintain oil pressure.
There is more but this post is too long already so lets keep it to basics.
Cheers
Simon
0w-40, 5w-40, 10w-40 and 15w-40 are all the same thickness (14cst) at 100degC.
Centistokes (cst) is the measure of a fluid's resistance to flow (viscosity). It is calculated in terms of the time required for a standard quantity of fluid at a certain temperature to flow through a standard orifice. The higher the value, the more viscous the fluid.
As viscosity varies with temperature, the value is meaningless unless accompanied by the temperature at which it is measured. In the case of oils, viscosity is generally reported in centistokes (cst) and usually measured at 40degC and 100degC.
So, all oils that end in 40 (sae 40) are around 14cst thickness at 100degC.
This applies to all oils that end in the same number, all oils that end in 50 (sae 50) are around 18.5cst at 100degC and all oils that end in 60 (sae 60) are around 24cst at 100degC.
With me so far?
Great!
Now, ALL oils are thicker when cold. Confused? It's true and here is a table to illustrate this.
SAE 40 (straight 40)
Temp degC.........................Viscosity (thickness)
0..........................................2579cst
20..........................................473cst
40..........................................135cst
60..........................................52.2cs t
100........................................ 14cst
120.........................................8.8cst
As you will see, there is penty of viscosity at 0degC, in fact many times more than at 100degC and this is the problem especially in cold weather, can the oil flow quick enough to protect vital engine parts at start up. Not really!
So, given that an sae 40 is 14cst at 100degC which is adequate viscosity to protect the engine, and much thicker when cold, how can a 0w oil be too thin?
Well, it can't is the truth.
The clever part (thanks to synthetics) is that thin base oils can be used so that start up viscosity (on say a 5w-40 at 0degC) is reduced to around 800cst and this obviously gives much better flow than a monograde sae 40 (2579cst as quoted above).
So, how does this happen, well as explained at the beginning, it's all about temperature, yes a thin base oil is still thicker when cold than at 100degC but the clever stuff (due to synthetics again) is that the chemists are able to build these oils out of molecules that do not thin to less than 14cst at 100degC!
What are the parameters for our recommendations?
Well, we always talk about good cold start protection, by this we mean flow so a 5w will flow better than a 10w and so on. This is why we recommend 5w or 10w as the thickest you want to use except in exceptional circumstances. Flow is critical to protect the engine from wear!
We also talk about oil temps, mods and what the car is used for. This is related to the second number xw-(XX) as there may be issues with oil temperatures causing the oil to be too thin and therefore the possibility of metal to metal contact.
This is difficult to explain but, if for example your oil temp does not exceed 120degC at any time then a good "shear stable" sae 40 is perfectly capable of giving protection.
"Shear stability" is important here because if the oil shears it thins and that's not good!
However, if you are seeing temperatures in excess of 120degC due to mods and track use etc then there is a strong argument to using an sae 50 as it will have more viscosity at these excessive temperatures.
There are trade offs here. Thicker oils cause more friction and therefore more heat and they waste power and affect fuel consumption so it's always best to use the thinnest oil (i.e. second number) that you can get away with and still maintain oil pressure.
There is more but this post is too long already so lets keep it to basics.
Cheers
Simon
So should I change it for 20-50 then ?
This oil business is VERY confusing to a non technical person like me. I have to rely on others (i.e. oil sales people & the like) to advise & when I purchased the Helix 5W-40, they guy had looked up TVR 4.5 Chim in his little book & the 5W-40 was what was recommended. Castrol's guide also refers to 10-40 I'm told. As the engine is working much harder than the average (as I say, my Chim is really only used for track days now) I'm obviously keen to do the right thing.
>> Edited by 55jnj on Monday 20th June 19:10
This oil business is VERY confusing to a non technical person like me. I have to rely on others (i.e. oil sales people & the like) to advise & when I purchased the Helix 5W-40, they guy had looked up TVR 4.5 Chim in his little book & the 5W-40 was what was recommended. Castrol's guide also refers to 10-40 I'm told. As the engine is working much harder than the average (as I say, my Chim is really only used for track days now) I'm obviously keen to do the right thing.
>> Edited by 55jnj on Monday 20th June 19:10
yes your right oil is confusing but so is everything when you are seeking advice you cans ask 20 different people the same question and i bet you get 20 differtent opinions!! all i can go on is 20 yrs of expeience with the rover engine and the thicker oil you can use the better off you are, motul were to my knowledge one of the first componies to use esters in their oils which is why i am fond of them the downside is, it is not that easy to get hold of? i would recomend 15/50 if you are running an oil cooler if not run with their 20/60, if you have trouble finding them go for the 10/60 castrol rs
rob
>> Edited by v8 racing on Monday 20th June 19:55
rob
>> Edited by v8 racing on Monday 20th June 19:55
No, don't do it, its not right. You simply don't need 24cst at 100degC (sae 60}. An sae 50 tops, 10w-50 would be my choice as it's got better cold start than 15w-50 and is still 18.50cst at 100degC.
Now if your oil temps always remain below 120degC then I would even recommend a 5w-40 as the best option. Most engines (modern that is) need between 10cst and 15cst maximum and anything above that just causes friction leading to more heat and also wastes power.
Look at this carefully and decide for yourself, it's not hard to understand. A thicker oil is not better unless it's an extreme situation!
The question is, at what (sump) temperature is the oil at a viscosity that suits a modern high-RPM engine.
Present day designs seem happy on an oil viscosity of 10 to 15 cSt. (But many are OK on less than 10.) 30cSt is too high at high RPM. It can lead to foaming, air entrainment and cavitation.
Temp.for 30cSt(Deg. C).Temp.for15cSt.Temp. for 10cSt
5W/40....71.................90.................117
10W/40...70.................99.................118
10W/50...80................109.................130
10W/60...89................119.................142
This shows that a 5W/40 or a 10W/40 is perfectly adequate for all engines except those that run an unusually high temperatures.
So long as you can get adequate oil pressure, thin oils have far more benefits so don't be fooled to believing otherwise.
Cheers
Simon
Now if your oil temps always remain below 120degC then I would even recommend a 5w-40 as the best option. Most engines (modern that is) need between 10cst and 15cst maximum and anything above that just causes friction leading to more heat and also wastes power.
Look at this carefully and decide for yourself, it's not hard to understand. A thicker oil is not better unless it's an extreme situation!
The question is, at what (sump) temperature is the oil at a viscosity that suits a modern high-RPM engine.
Present day designs seem happy on an oil viscosity of 10 to 15 cSt. (But many are OK on less than 10.) 30cSt is too high at high RPM. It can lead to foaming, air entrainment and cavitation.
Temp.for 30cSt(Deg. C).Temp.for15cSt.Temp. for 10cSt
5W/40....71.................90.................117
10W/40...70.................99.................118
10W/50...80................109.................130
10W/60...89................119.................142
This shows that a 5W/40 or a 10W/40 is perfectly adequate for all engines except those that run an unusually high temperatures.
So long as you can get adequate oil pressure, thin oils have far more benefits so don't be fooled to believing otherwise.
Cheers
Simon
i see what your saying simon however on the rover engine if you put 40 grade oil in it and spend 10 minutes on a track then let it idle your oil pressure has gone from 45 -50 psi at idle to as low as 10?? and at 4000 rpm you have gone from 60 psi cold to 35 psi and at 6000 rpm you still get no more than 35 psi with hot oil?? with a 60 it is fine??
The quality of the oil is important here.
What's happening is the oil is over-thinning due to shearing and therefore losing viscosity. As I and my brother Guy have said on many occasions you need a good low viscosity shear stable oil that will not break down.
A petroleum based sae 40 will shear extremely quickly when subjected to punishment, a shear stable proper synthetic oil will see in some cases 10 track hours without shearing unless of course you're seeing silly oil temperatures or major fuel dilution.
This is all down to quality. Synthetics don't need the same level of viscosity improvers to work as the basestocks are more thermally stable. You see this is the component that shears and causes viscosity loss and the perfect oil has none at all in it.
If thicker is better then how do you explain that F1 cars and Superbikes run 0w-20 at temps of 155degC plus? Surely this oil would just break apart? It doesn't and the reason why is because it's a combination of narrow viscosity range (20) and very stable basestocks (normally a high percentage of esters as used in aero engines) meaning that no viscosity improvers are required at all as the oil suffers no shear loss in service although other addatives can be used up.
Viscosty Index Improvers are long chain polymers that remain coiled when cold and uncoil with heat, assisting the oil to fight back against viscosity loss.
I hope this explains some more, there's really too much to explain at one time without totally losing people.
Cheers
Simon
What's happening is the oil is over-thinning due to shearing and therefore losing viscosity. As I and my brother Guy have said on many occasions you need a good low viscosity shear stable oil that will not break down.
A petroleum based sae 40 will shear extremely quickly when subjected to punishment, a shear stable proper synthetic oil will see in some cases 10 track hours without shearing unless of course you're seeing silly oil temperatures or major fuel dilution.
This is all down to quality. Synthetics don't need the same level of viscosity improvers to work as the basestocks are more thermally stable. You see this is the component that shears and causes viscosity loss and the perfect oil has none at all in it.
If thicker is better then how do you explain that F1 cars and Superbikes run 0w-20 at temps of 155degC plus? Surely this oil would just break apart? It doesn't and the reason why is because it's a combination of narrow viscosity range (20) and very stable basestocks (normally a high percentage of esters as used in aero engines) meaning that no viscosity improvers are required at all as the oil suffers no shear loss in service although other addatives can be used up.
Viscosty Index Improvers are long chain polymers that remain coiled when cold and uncoil with heat, assisting the oil to fight back against viscosity loss.
I hope this explains some more, there's really too much to explain at one time without totally losing people.
Cheers
Simon
stevieturbo said:
Any possibly power gains from running a thin oil, are absolutely minute, compared to the risks they could pose to an engine.
I'm sorry but I have to disagree, with power gains being minute. It depends what power you are running and how important it is to you.
Have a read of this and you'll see what I mean:
Must Have MORE Power!
Motorcars are bought for all sorts of reasons, but enthusiasts like lots of power.
To get more power, a lot of fuel must be burnt, and more than half of it, sadly, gets thrown away as waste heat. For every litre of fuel burnt, 60% of the energy goes as waste heat into the exhaust and cooling system.
A turbocharger can extract a few percent as useful energy and convert it into pressure on the intake side, but only 40-45% is left, and only 25% actually shows up as BHP at the flywheel. 6% goes in pumping air into the engine, 6% as oil drag losses and 2-3% as engine friction.
The oil deals with 97% of the friction; so reducing the remaining few percent is not easy. If you doubt that even ordinary oil has a massive effect, take a clean, dry 200 bhp engine, connect it to a dyno and start it up. It will only make 1 bhp for a few seconds. Now that’s real friction for you!
Oddly enough, people get starry-eyed about reducing friction, especially those half-wits who peddle silly “magic additives”, which have not the smallest effect on friction but rapidly corrode bearings and wallet contents. In fact, even a virtually impossible 50% reduction in the remaining engine friction would be no big deal, perhaps one or two bhp or a couple of extra miles per gallon.
Even More Power!
He place to look for extra power is in that 6% lost as oil drag. In a well-designed modern motor, the oil doesn’t have to cover up for wide clearances, poor oil pump capacity or flexy crankshafts, so it can be quite thin.
How thin? Well take a look at these dyno results.
A while ago now, we ran three Silkolene performance oils in a Honda Blackbird motorcycle. this fearsome device is fitted with a light, compact, naturally aspirated 1100cc engine which turns out 120+ bhp at the back wheel.
The normal fill for this one-year-old engine was 15w-50, so the first reading was taken using a fresh sump-fill of this grade. (The dyno was set up for EEC horsepower, i.e. Pessimistic)
15w-50
Max Power 127.9 bhp @ 9750 rpm
Torque 75.8 ft-lbs @ 7300 rpm
After a flush-out and fill up with 5w-40 the readings were;
5w-40
Max Power 131.6 bhp @ 9750 rpm
Torque 77.7 ft-lbs @ 7400 rpm
Then we tried an experimental grade, 0w-20 yes, 0w-20! This wasn’t as risky as you may think, because this grade had already done a season’s racing with the Kawasaki World Superbike Team, giving them some useful extra power with no reliability problems. (But it must be said, they were only interested in 200 frantic miles before the engines went back to Japan)
0w-20
Max Power 134.4 bhp @ 9750 rpm
Torque 78.9 ft-lbs @ 7400 rpm
In other words, 3.7 bhp / 2.9% increase from 15w-50 to 5w-40
A 2.8 bhp / 2.1% increase from 5w-40 to 0w-20
A 6.5 bhp / 5% overall. Not bad, just for changing the oil!
More to the point, a keen bike owner would have paid at least £1000 to see less improvement than this using the conventional approach of exhaust/intake mods, ignition re-mapping etc.
Cheers
Simon
This is now confusing me as well!! personally i dont think you can compare the rover engine to modern f1 cars and the like, i have only looked inside one f1 engine and the oil system is very well controlled with small oil galleries and copetition pumps way beyond the stock rover system with massive clearences and oil galleries?
I am not for one moment saying you are wrong in anyway but when we have tried 40 grade oil various products they have been next to useless some even put the oil light on at idle? i would love to know more about the oil grade issue so maybe you could mail me direct? thanks ps what brand and viscosity would you recomend then for a rover engine making 300 bhp a tuned griff for instance
I am not for one moment saying you are wrong in anyway but when we have tried 40 grade oil various products they have been next to useless some even put the oil light on at idle? i would love to know more about the oil grade issue so maybe you could mail me direct? thanks ps what brand and viscosity would you recomend then for a rover engine making 300 bhp a tuned griff for instance
opieoilman said:
In a well-designed modern motor ...
Two questions:
How well does this apply to the RV8?
Does the oil viscosity affect the distribution significantly? I mean there are plenty of parallel paths through the engine, does each path still get it's fair share if you drop the viscosity and pressure, or does it all end up nipping back down the first shortcut it can see?
I had good oil pressure, and never any concerns running Motul 300v Competition 15/50 in my 4.6 Twin turbo RV8. It had around 450-500bhp, on a totally std short motor, and when I stripped it after about 18 months after it melted a piston, the bearngs etc and everything else internally, was absolutely mint.
That would be enough to convince me its more than adequate for any Rover V8 engine.
That would be enough to convince me its more than adequate for any Rover V8 engine.
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