Rotella T4 15w40 + Lucas in a 93 Corvette Autocross Race Car

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Robvette said:
The 5w30 factory fill was prescribed to meet CAFE fleet fuel economy targets. Not to protect a 30 year old engine being run at WOT, over and over and over. In AX it'll rarely be shifted into 3rd, but it will go WOT to near the redline repeatedly.
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Depends on the oil temperature. What's the oil temperature at the start of the Auto-X? Running an Auto-X course in 60 seconds isn't going to raise the sump temperature much at all. What oil temps does this car see in a typical Auto-X event? Info from the previous owner available?
 
cheesepuffs2 said:
As for the previous owner of your car overfilling by a quart to prevent oil starvation at high Gs during autocross, yikes. Overfilling can cause whipping/foaming of the oil. Oil starvation issues are rare during HPDEs, let alone during autocross where there are no long, sustained corners where there would actually be time for the oil to pack over into one side of the sump away from the pickup anyway. I would advise against continuing that practice.
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The C5 OM says to put an extra quart in for track events. Maybe the C4 OM says something similar.
 
ZeeOSix said:
Depends on the oil temperature. What's the oil temperature at the start of the Auto-X? Running an Auto-X course in 60 seconds isn't going to raise the sump temperature much at all. What oil temps does this car see in a typical Auto-X event? Info from the previous owner available?
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The car has a Dewitt 4-row Al radiator w big cooling fans and a 160° thermostat. Even while waiting in the queue with the AC on a hot day it’s not going much over 180 and during race runs I don’t think it is even getting to 200. LT1s commonly run 220+ in conditions like this, the prior owner wanted it to easiily run cooler than that. There is not a lot of time between race runs - so not much cooling occurs. My oldest son and I will co-drive this car too, which means twice as many race runs and very little time between runs.
 
Robvette said:
The car has a Dewitt 4-row Al radiator w big cooling fans and a 160° thermostat. Even while waiting in the queue with the AC on a hot day it’s not going much over 180 and during race runs I don’t think it is even getting to 200. LT1s commonly run 220+ in conditions like this, the prior owner wanted it to easiily run cooler than that. There is not a lot of time between race runs - so not much cooling occurs. My oldest son and I will co-drive this car too, which means twice as many race runs and very little time between runs.
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Can't go by the coolant temperature to determine the oil temperature. Does this car have an accurate oil temperature gauge of any kind?
 
ZeeOSix said:
Can't go by the coolant temperature to determine the oil temperature. Does this car have an accurate oil temperature gauge of any kind?
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It does. It has both digital oil and coolant temperature gauges. I have seen oil temperature is over 200, I will report back after our first event.
 
Robvette said:
It does. It has both digital oil and coolant temperature gauges. I have seen oil temperature is over 200, I will report back after our first event.
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Just driving grocery getting cars on the streets without even revving them very high will get oil over 200F.
 
My Tahoe cruises with 205°F coolant temp and 220-230°F oil temp. A friend's twin turbo 363ci Mustang cruises with 180-190°F coolant temp and 250-260°F oil temp.
 
Serious question, is the 15W-50 choice in reaction to hitting low-200 degree oil temp? Because if so then a thinner oil than that will reduce pumping losses, free up a slight bit of HP, and will still handle 200 degrees 100% fine.
 
cheesepuffs2 said:
Serious question, is the 15W-50 choice in reaction to hitting low-200 degree oil temp? Because if so then a thinner oil than that will reduce pumping losses, free up a slight bit of HP, and will still handle 200 degrees 100% fine.
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No. 40 and 50 weight oils reduce wear, extend optimal performance life and the horsepower and fuel economy penalties are negligible.
 
ZeeOSix said:
Just driving grocery getting cars on the streets without even revving them very high will get oil over 200F.
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I just bought this car Sunday and drove it home from Madison Wisconsin to Roanoke Virginia.

The car runs outstandingly well, but that type of driving isn’t very relevant.

If you want to bold / focus on part of my statement it should be “I will report back after our first event”.
 
Robvette said:
No. 40 and 50 weight oils reduce wear, extend optimal performance life and the horsepower and fuel economy penalties are negligible.
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Thicker oils reduce wear when the engine is running high enough oil temperatures to lower MOFT to detrimentally thin levels. Think of it like added headroom. I know you've already said you'll report back with temps after your first event, which is cool, but you aren't going to see high enough temps during autocross to see a wear difference between a 30 and a 50 weight oil. They will be effectively the same level of protection. Run whatever, I'm not disuading you from running anything you like, I'm just saying it is not going to matter.
 
Robvette said:
I just bought this car Sunday and drove it home from Madison Wisconsin to Roanoke Virginia.

The car runs outstandingly well, but that type of driving isn’t very relevant.

If you want to bold / focus on part of my statement it should be “I will report back after our first event”.
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The only time you'll see oil temperatures barely break the 200F mark after a 60 second Auto-X is if the oil is 198F when you leave the starting line, lol. That was kind of my point on the previous bold text focus.
 
Robvette said:
Oil changes are 4.5
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Have you thought about running an Oil Accumulator, instead of overfilling your oil. I think they come in 2 or 3 quart capacities. So basically you would have 6.5 or 7.5 quarts of oil on hand. This adds oil when you need it, and when you do not need it, then it goes back in the Oil Accumulator.

4.5 quarts might be ok if old Joe, is going to a car show and driving below the speed limit.
 
cheesepuffs2 said:
What makes you feel that 4.5 quarts (so probably actually a 5 quart total capacity if that's the change amount) isn't enough?
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Because with the type of driving the OP is doing, he really needs a Dry Sump Oil System which is now on the new Corvette with the LT2 Engine. If not then the next best thing is an Oil Accumulator. If we could put a clear oil pan on the OP's car and take a video while he does his race thing, you would change your mind.
 
Brian123 said:
Because with the type of driving the OP is doing, he really needs a Dry Sump Oil System which is now on the new Corvette with the LT2 Engine. If not then the next best thing is an Oil Accumulator. If we could put a clear oil pan on the OP's car and take a video while he does his race thing, you would change your mind.
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He does not need a dry sump... I could maybe see a baffled oil pan if he's running HPDEs with some really long sweepers, but c'mon. You're overestimating the "racing" thing here, big time.
 
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