We have dropped the viscosity in the GTO 408 down to Pennzoil Platinum 10-30 from various 5-40/10-40's with excellent results. We have a large oil cooler that keeps the oil at 180f even after hard runs and abuse on Main St. from time to time. OCI's are 500 miles or roughly 15 hours of engine run time.We run dual Amsoil filters so we have roughly an 8qt sump with all the plumbing. Fuel Dilution is 5-20 with some serious TBN/HTHS and am curious if I should give it a shot for 500 miles of pure abuse and see what we get.....any thoughts? Comments? Predictions of equal or better wear/doom? Never thought I'd even consider a 20wt in a 408 Stroker...but I'm leaning towards a test of it.....
"Cool" High Performance oil viscosity choice
- Thread starter SargeGTO
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I don't think a UOA will tell you how well a thinner oil protects. If this view is accepted, then you wouldn't really being doing a test.
JAG...can you elaborate for me please.
What are your main and rod clearances? also need to consider the additional thrust loads of the rod/stroke ratio in that motor. Myself, if its not a race car after another tenth of a sec and blueprinted for thin oil, I wouldn't go there.
I would give it a try. You might even see lower oil temps as a result of using 5w20. More flow = better cooling and lubrication, and w/ that big a sump you have plenty of oil.i am currently using 5w20 in two of my cars that spec 5w30, and am very pleased so far. I would stick w/ the PP 5w20.
joe
I have not noticed UOA wear metal differences due to people using even vastly different viscosity oils than recommended, yet automakers are not all specifying 0W-20. Basically, I don't think typical UOAs are good wear-ometers due to many technical reasons.
What kind of results are you talking about? What are the advantages of 10W-30 over 5W-40?
We had much higher wear metals with the 40 weights. 30 weights dropped the wear metals significantly.
We have .001 to .0015 clearances.With the original LS1 we saw .002-.0025. Motor was custom built and we used only the "best"....very well balanced. With the low oil temps and tight clearances I am thinking a stout 20 weight will work well and gain a noticeable ( maybe a tenth)
without sacrificing wear.
I have seen and have been told by "the learned" that thicker oils, in very tightly built motors, that the thicker oil doesn't "get into" those tight bearing clearances thus causing the excessive wear. And I've confirmed this with 40 weights versus the 30 weights in this motor. So my thought process is a 20 weight, in a cooler environment ( under 190f oil temps), will lubricate even better without sacrificing wear. My concern is film strength under pressure. And of course how well it will hold up to fuel dilution.
Yes, with smaller bearing clearances it needs a thinner oil in those bearings. Of course that's just one part of the engine. As for the
BTW, are you using any magnets that you can check after each oil change? I like and use both FilterMag and MagnaGuard magnets (http://www.magna-guard.com/MagnaGuard.html).
BTW, are you using any magnets that you can check after each oil change? I like and use both FilterMag and MagnaGuard magnets (http://www.magna-guard.com/MagnaGuard.html).
Well the touch wood of my 20 weight "jihad" is exactly that....at 190f I wonder if a 30 weight is optimized and if not ( which I suspect) would a 20 weight be closer to optimized What I have found though, JAG, is this...thicker oils handle fuel dilution better than thin. Now I do not know about todays "new" 20 weights which have a stout TBN. So that is one consideration in choosing a viscosity for optimum performance without sacrificing wear. So considerations for me run like this...
1. Bearing clearances.
2. Oil Temps.
3. Fuel Dilution impact on the oil of choice.
My buddy Ray runs 0-7 weight in his 32 Ford altered...and of course he rebuilds the motor 4 times a year
and that after 7-8 "miles"
so I can appreciate the trade off between performance from lighter weight oils and the wear on the motor due the lack of the "film" protection offered by thicker oils.
Now I run a Pro Street car that my wife and I are getting ready to take to the grocery store this morning. I run 500 mile OCI's ( or less depending on the engine timer)and she runs 10 second 1/4 miles and 172mph flying miles....I am thinking I can run a 20 weight in there, with those OCI's and get better performance without sacrificing wear.....as long as the 20weight will hold up to the fuel dilution of 0.75 ( closed cup Dyson style)......I am curious of the performance of various viscosity oils that do not reach and maintain 212f for a period of time.....I ramble
And no I do not run magnets. Well one on the end of the drain plug....
1. Bearing clearances.
2. Oil Temps.
3. Fuel Dilution impact on the oil of choice.
My buddy Ray runs 0-7 weight in his 32 Ford altered...and of course he rebuilds the motor 4 times a year
Now I run a Pro Street car that my wife and I are getting ready to take to the grocery store this morning. I run 500 mile OCI's ( or less depending on the engine timer)and she runs 10 second 1/4 miles and 172mph flying miles....I am thinking I can run a 20 weight in there, with those OCI's and get better performance without sacrificing wear.....as long as the 20weight will hold up to the fuel dilution of 0.75 ( closed cup Dyson style)......I am curious of the performance of various viscosity oils that do not reach and maintain 212f for a period of time.....I ramble
Sarge, you'd actually reduce your viscosity windage losses by running your oil hotter. A 5W-30 oil at 212F generally has a lower viscosity than a 0W-20 oil at 180F. you didn't say how far you've dropped your oil temperature with the oil cooler, but you'll need to at least compensate for that with a lower viscosity oil.
From 200f fairly consistently with the small oil cooler to 180f with the large oil cooler. I just ran her down the highway 30 miles (3 gallons of Shell 93
)to and from town and never got over 175f...that is in town/stop lights/highway cruising at 75mph. Ambient temps here today are 70-72f. And yes I understand a 30 weight at 100c is "thinner"...thus my curiosity on going a 20 weight with oil temps at 180f.
I have just a little to go on this OCI...then it goes off to Terry....I may just try some Amsoil 0-20 or Pennzoil Platinum 5-20 and see....I cannot see how I'm going to trash this motor with it....maybe just a 10hr engine run time on it and see where I'm at.
I have just a little to go on this OCI...then it goes off to Terry....I may just try some Amsoil 0-20 or Pennzoil Platinum 5-20 and see....I cannot see how I'm going to trash this motor with it....maybe just a 10hr engine run time on it and see where I'm at.
Is there a chart reflecting viscosity for various weights of oil at certain temps?
Sarge, I've got a table that I copied from "somewhere" on BITOG that I can no longer remember, or find in a search, for a few oils. If anyone knows where it comes from, I'd be happy to give the originator credit.
That is helpful...and thank you for taking the time to post that. I assume this is in Fahrenheit? I do see the 20 weights are thinner at 150 than 30 weights. Now at least I can chart fuel dilution with viscosity across the temp range. Or should I say what it "should" be
I'll make assumptions/averages from previous UOA's with flash points after 500 mile UOA's and back into a chartable trend. I guess I will have fuel dilution/viscosity from historical numbers on one side and use this chart ( for a guide) and historical wear numbers on the bottom side. This should show me where the oil weight in a known fuel diluted environment reaches optimum protection with minimum viscosity utilized. I'll work on it....
The temps are in C, not F.
Thanks........
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