Engine oil Viscosity

fvracer27
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Engine oil Viscosity

Post by fvracer27 »

What are most using for our engines?
Mark Filip
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SR Racing
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Re: Engine oil Viscosity

Post by SR Racing »

I suspect most all are using 10W-30 synthetic. (Or a 30 labeled oil like Red Line, but it is actually a 10W-30)
fvracer27
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Re: Engine oil Viscosity

Post by fvracer27 »

Jim what do you think about 5W30 or 5w40 so the oil is a little thinner on start up? With the full Flow type of systems the oil pressure is through the roof until the engine warms up and 2 weekends ago it was extremely cold here in NH and on start up my data showed 132lbs at idle and I was rushing to swap tires and make it to grid and as soon as I left the garage oil pressure saw 172lbs ! and popped the oil filter seal blowing 3 qts out in 3 secs. I have some friends that run Grand AM endurance cars (V8) and they run 0w20. They do run a dry sump.
Mark Filip
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FVartist42
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Re: Engine oil Viscosity

Post by FVartist42 »

We ran 20W Redline at the runoff last year, since it was so cold. Normally we run 30W Redline on the left coast, since the weather is normally above 75.
fvracer27
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Re: Engine oil Viscosity

Post by fvracer27 »

FVartist42 wrote:We ran 20W Redline at the runoff last year, since it was so cold. Normally we run 30W Redline on the left coast, since the weather is normally above 75.

Which Redline? Is it a straight 30W? And is it synthetic?

I got the answer as I asume your using the 20wt when cold and 30wt racing oil when warmer
Mark Filip
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hardingfv32-1
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Re: Engine oil Viscosity

Post by hardingfv32-1 »

Ambient temps are not directly relevant. Your decision is based on your engine operating temperature. Ballpark... 30w @ 210F is considered a good starting point. Every 30 deg is a one grade change in oil viscosity. So, @ 180F you could use 20w or @ 240F you would use 40w. This is all relates to having the proper viscosity for the engine. It does not consider the effects of oil temps on different parts of the engine.

Brian
FVartist42
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Re: Engine oil Viscosity

Post by FVartist42 »

Redline racing oil.
SR Racing
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Re: Engine oil Viscosity

Post by SR Racing »

Yes, when cold it would be ok to go to a 20W. (This is what we do.) Just make sure your OP is adquate. (When in doubt you can always mix blends to achieve a 25 weight, etc.)

30 weight race oils (RedLine etc.) while marked 30, do in fact contain viscosity indexers and are really the same as 10W-30. (See the back of the bottle)
The big difference is the additive package in the race oil. Less detergents and Zinc, etc. This you want.
With our Valve trains and clearances (and strange engine design :) ) it is not a good idea to go under 20 weight. If your engine oil temp is 220 or under at the end of the race (and OP is good), a 20 is fine and gets you a bit more HP.
Note the "W" in 10W-30 means Winter. ie. It is a 30 weight oil that acts like a 10 in the winter. Synthetic oils are in fact a bit better than this due to their composition and cold pour rate.

I don't understand why so many people use a full flow system. When bypass and relief valves are working right, it is not needed (for cooling or OP) and you can get the problems you have seen. With a full flow system you are also giving up some early lap HP.

Hope that helps.

While Brian is correct, You can asume that with cold ambient temps your engine will cool better and thus oil temps lower.
fvracer27
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Re: Engine oil Viscosity

Post by fvracer27 »

Thanks Jim

So my engine is a full flow system was that way when I got it. So if I use a 5w30 race synthetic it would give me a little less OP at start ups while maintaining the protect of the 10w30 I currently run? With my D13 I would see temps creeping 250 on hot days, in my Womer 212 was the highest I have seen so far on hot hot days. A few weeks ago at NHMS with temps around 40 deg and blocking off oil cooler it was crazy low oil temps (172 highest) in the dry about 48deg air temp at that point and I warmed the car up on grid temp got to 110 rolling on track
Mark Filip
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fvracer27
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Re: Engine oil Viscosity

Post by fvracer27 »

hardingfv32-1 wrote:Ambient temps are not directly relevant. Your decision is based on your engine operating temperature. Ballpark... 30w @ 210F is considered a good starting point. Every 30 deg is a one grade change in oil viscosity. So, @ 180F you could use 20w or @ 240F you would use 40w. This is all relates to having the proper viscosity for the engine. It does not consider the effects of oil temps on different parts of the engine.

Brian

Thanks Brian that's a nice easy way to look at it.
Mark Filip
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Re: Engine oil Viscosity

Post by SR Racing »

fvracer27 wrote:So if I use a 5w30 race synthetic it would give me a little less OP at start ups while maintaining the protect of the 10w30 I currently run?
That is correct. I doubt you would notice any real change in OP even at startup since the 5W (Winter) performance doesn't come into much play until below freezing.
fvracer27
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Re: Engine oil Viscosity

Post by fvracer27 »

SR Racing wrote:
fvracer27 wrote:So if I use a 5w30 race synthetic it would give me a little less OP at start ups while maintaining the protect of the 10w30 I currently run?
That is correct. I doubt you would notice any real change in OP even at startup since the 5W (Winter) performance doesn't come into much play until below freezing.
Yes I just was reading last night (maybe a little to much reading) and I remember seeing that.
Mark Filip
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Rickydel
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Re: Engine oil Viscosity

Post by Rickydel »

data showed 132lbs at idle and I was rushing to swap tires and make it to grid and as soon as I left the garage oil pressure saw 172lbs
Mark,
Do you know what size oil pump is in your engine?
fvracer27
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Re: Engine oil Viscosity

Post by fvracer27 »

Rickydel wrote:
data showed 132lbs at idle and I was rushing to swap tires and make it to grid and as soon as I left the garage oil pressure saw 172lbs
Mark,
Do you know what size oil pump is in your engine?
I do not know but it pumps like crazy
Mark Filip
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brian
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Re: Engine oil Viscosity

Post by brian »

Since we are required to run the spec pump I would be surprised to see anything other than the thinner pump. If you are experiencing those high pressures, your engine may have a overly strong spring on the relieve piston next to the flywheel. Often these spring rates are increased to increase oil pressure when hot.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
sharplikestump
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Re: Engine oil Viscosity

Post by sharplikestump »

fvracer27 wrote:Jim what do you think about 5W30 or 5w40 so the oil is a little thinner on start up? With the full Flow type of systems the oil pressure is through the roof until the engine warms up and 2 weekends ago it was extremely cold here in NH and on start up my data showed 132lbs at idle and I was rushing to swap tires and make it to grid and as soon as I left the garage oil pressure saw 172lbs ! and popped the oil filter seal blowing 3 qts out in 3 secs. I have some friends that run Grand AM endurance cars (V8) and they run 0w20. They do run a dry sump.
Mark,
Are you still experiencing the outrageous oil pressure?
fvracer27
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Re: Engine oil Viscosity

Post by fvracer27 »

Well during the warmer weather it is high but not like it was when it was chilly. I just have to remember to get the engine up to at least 100 deg before any real rpms are reached. I'm was still running 10W30 and my season is over now.
Mark Filip
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sharplikestump
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Re: Engine oil Viscosity

Post by sharplikestump »

fvracer27 wrote:Well during the warmer weather it is high but not like it was when it was chilly. I just have to remember to get the engine up to at least 100 deg before any real rpms are reached. I'm was still running 10W30 and my season is over now.
Here's the deal....That weight oil should be just fine. Your problem is caused by one or more of the following situations:
A stuck plunger in the oil bypass port (flywheel end), or an EXTREMELY stiff spring.
An enormous oil pump. If everything else is right, just having the 26mm gears would not cause pressure to be THAT extreme.
Finally, I can practically guarantee that your block has not been modified to handle the higher pressures that we generate with higher revs on cold oil. An indication of this being the case is if upon starting the engine at a temp where the pressure is reasonable, and by slowly raising the revs you see the gauge hold at approximately 42 psi for maybe 500-1,000 additional revs, but then it starts climbing from there, the case was not worked. It is a simple procedure, but can only be done on a bare case.
Mike P.
fvracer27
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Re: Engine oil Viscosity

Post by fvracer27 »

I don't think it's the case but I could be wrong. When at normal temps meaning engine warm and oil temp at 170+ looking at my date the pressure is perfect. As long as the oil gets warm there seems to be no problems.
Mark Filip
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sharplikestump
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Re: Engine oil Viscosity

Post by sharplikestump »

fvracer27 wrote:I don't think it's the case but I could be wrong. When at normal temps meaning engine warm and oil temp at 170+ looking at my date the pressure is perfect. As long as the oil gets warm there seems to be no problems.
It should be no different (or only SLIGHTLY higher) at 80 degrees F.
HAndyalbert11
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Re: Engine oil Viscosity

Post by HAndyalbert11 »

What would minimum pressure at hot idle be? Oil temp 237 pressure at idle is about 9 psi.
satterley_sr
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Re: Engine oil Viscosity

Post by satterley_sr »

The normal VW oil light comes on at about 3-6 psi. So, 9psi seems to be ok.
jphoenix
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Re: Engine oil Viscosity

Post by jphoenix »

Dietmar told me a min. of 27 psi on the straight, high rpm. My low oil press light is set at 7 psi, I've seen it flicker at idle when real hot.
Jim Phoenix
2016 Red Mercury FV 44
brian
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Re: Engine oil Viscosity

Post by brian »

Lots of great posts and I agree with almost everything. Current research has begun to identify oil flow as being more important than oil pressure in preventing bearing damage. This study assumes film strengths achieved by synthetic oils. Organic based oils have less film strength given the same viscosity.

High oil flows cool better; moves foreign material better and aids in film strength. Oil pressure is a measure of resistance to flow and high oil pressure costs HP. Before engine rules were implemented in NASCAR, they would qualify on 0 weight and not worry about the life of the motor since the hp would only be used for one lap.

I have always preferred full flow systems. There are pluses and minuses, but nothing gets into my engines before getting filtered. I know that all the oil in a partial flow system gets filtered, eventually. With our soft aluminum bearings, FOD and can be critical and is a common reason for failures.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
satterley_sr
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Re: Engine oil Viscosity

Post by satterley_sr »

FOD?
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