Standard motor oil vs racing oil, and what weight? Chump Car content

Currently prepping a '89 BMW 325i for chump car endurance events. The discussion has turned to which motor oil to use. Motor has approx 200k miles on it but shows good compression (150-150-148-152-150-150), and actually runs really well. Have not been able to run it enough yet to monitor oil consumption, but plan is to test at track day in the spring prior to events. Part of me says go with the cheap synthetic and save the money already, makes no difference, The other, more cautious side, says stop being a cheap ass and use the right stuff. I was considering 40wt from Redline which is the weight they recommend for this engine (2.5L 6cyl). Any thoughts or experiences using different oils in these endurance events would be greatly appreciated.

I would use a good synthetic, and being an older high mileage thing, I would probably use 15w40, or even a 20w50. The killer will be heat, and the synthetic will deal with that better.

Can't go wrong with good old Mobil 1.

See what your oil temps are on a practice run. If they are atomic, run a better oil. If they a normal (270ish range), they go with cheaper synthetic.

KJ

For our Lemons car, a Civic, we went through the same thought process, and in the end, are using a good quality store bought synthetic (Pennzoil Ultra). I'd use redline if I could get it locally, and probably will next year when the car has a turbo on it.

Even though this is cheap car racing, the extra cost to run a proper oil isn't much, and why not give the car every chance you can. I would hate to nuke a motor, and are changing it at 2 AM and then be thinking "what if had run the right oil, would this have happened?"

Bob The Oil Guy will give you all the answers you are looking for. It will take about an hour to go through it all but well worth it.

In a nut shell a good synthetic will work, if memory serves.

Good Luck

In the Civic we ran the cheapest stuff we could find. Advance brand oil this year and Rotella last. Changed the oil and filter Saturday night after the first 8 hours. Up to 7200 rpms for 30+ hours so far.

Streetwiseguy wrote: I would use a good synthetic,

As opposed to a lousy synthetic?

Streetwiseguy wrote: I would use a good synthetic, and being an older high mileage thing, I would probably use 15w40, or even a 20w50. The killer will be heat, and the synthetic will deal with that better. Can't go wrong with good old Mobil 1.

Stock weight is 20w50, for reference.

Rotella is good stuff used it in a Miata, worked wonderfully.

Didn't think you would want to give up the horsepower.

Rotella T is a wonderful miracale lube. Almost like snake oil.

:)

FlightService wrote: Rotella T is a wonderful miracale lube. Almost like snake oil.

My whole fleet runs Rotella T6. WRX, Cruiser, SV650, XR600. I wish I had room for a drum of the stuff.

Our Lemons / Chump 240Z runs a thick version of Rotella (maybe 20W50?), not synthetic and about $16 / jug at Wal-Mart. Never had a problem with consuming oil, and oil pressure and temps very stable. We only change the oil between events and have run it 24 hours at a time with no (apparent!) problems.

We could definitely go with a thinner oil, but the stuff is cheap and we've had great luck with maintaining oil pressure on our $500 car >>> one less headache.

Zomby woof wrote:

Streetwiseguy wrote: I would use a good synthetic,

As opposed to a lousy synthetic?

Yes, as opposed to something that barely meets the legal definition of synthetic, and isn't actually tested to meet any manufacturers standards.

Actual E30 racing content: I'd been running Castrol 20-50 in my E30 for the last couple of years. It's readily available at Wally Mart in 5 qt containers and works in half the other stuff I own. I change it every other race weekend, typically. Coming off the track when it's hot, the oil pressure would drop significantly over when it was fresh, enough that it would trigger the light at idle if I didn't keep the revs up. Not good.

This past race weekend I changed to 20-50 Valvoline racing oil. It was hotter than blazes all weekend, worse than I think I've ever experienced. Absolutely no change in my pressure reading after some severe racing. So yes, the racing oil is better and worth the price difference. Almost 170,000 on my E30's engine.

I don't use synthetic because of the cost coupled with the frequency of my changes, and the fact that it tends to leak out more on old/weak gaskets and seals (which my engine is loaded with). I don't doubt that it would work well but the over-the-NAPA-counter race oil seems to be an excellent compromise for my old engine.

well.. I think ddavid summed it up with some real world experience.

The 325i should have a factory oil cooler that works pretty well at controlling temps so if you are seeing high 270-ish stuff, check the thermostat (in the block, near the oil filter) and make sure the cooler is clean - they get packed with dirt.

I use full synthetic M1 over the dino stuff because it is supposed to be better at resisting shear at higher RPMs and temps. I don't actually know if it does... but my pressure never drops off.

Since my car does not actually know it is in a race and a race weekend is only 3hrs of on track - I change it once a season (or 20hrs whichever comes first) so the cost isn't really a concern. Blackstone labs says it is still good at that interval... I'd probably change it after a 24hr endurance race though ;)