9 replies to this topic

[Jim Venable]

Plenty of info about oil on the site. However I don't see anything about the below.

Normally 10W30 is the oil to run which we've run. Are there times when one might or would want to
run a 15W40 or a straight 30, 40 or 50 weight?

Thanks,
Nice Guy Jim

[davew]

We use (and sell) Redline, joe Gibbs, Royale Purple and Schaeffer and love them. We've installed dozens, and everybody comes up loving them. Simple, effective, done.

3 times in a row !!!!!

You can look at several reasons. If your engine is tired you may need some thicker oil for added oil pressure. At Gingerman in 105* heat we only had 25 psi at 7000. Added 1 qt thick oil and we jumped to 35psi. I have played around with oils on the dyno. Still have some more oils to try, but you can not say thin oil makes horsepower. I have run a 20-50 that made slightly more HP than a 10w. And a 0-20 that LOST 2 hp to the same 10w.

Dave

[Jim Venable]

Thank you Dave. Considering how busy you are, your unselfish willingness to take time to share your knowledge with all of us is
deeply appreciated by many. Definitely a class act.

Nice Guy Jim

[Keith Novak]

Back to the oil topic ... When breaking in an engine on the track, I've heard people say use dyno oil. I've used break-in oil and figured they meant the same thing. Is it the same thing or do they really mean dino (as in dinosaur) oil instead of synthetic and do people normally switch to something like break in oil for the dyno for some reason?

[Jim Drago]

We typically use a break in oil while at the shop and dynoing and breaking in. We then put in non synthetic, typically run the first day or 3-4 sessions, then switch to synthetic.

I used to use redline, no problems, but it is dark blue, it looks dirty in the car even when new. I switched to a lighter wheat colored oil as it is easier when to see when it gets dirty, but hard to see on the dipstick.

Jim

[Keith Novak]

Why break-in (or dyno) oil on the dyno then? Obviously different oils can make a bit of difference so is it to get a baseline to compare from or is there something about the additives for the shorter pulls compared to track use?

[Jim Boemler]

The goal is to lubricate the cylinder walls a little less effectively, so the rings seat ("seating" can be read as "wearing very fast for a little while). If you tear down many old Miatas, you'll see cylinder walls with the original hone marks -- caused by gentle break-in, making sure the rings can never seal fully. The idea is to let the rings and walls wear to mate up, and THEN lube them effectively so they won't wear after that. For the same reason, the best break-in is racing, not kindness, so that the rings are forced out into the walls as much as possible.

So yeah, dinosaur oil, both because it isn't as slick, and because it's cheaper. Wring the snot out of it, then change to the good stuff. Sadly, I've never been able to do that, since I've always had to drive to the track.

[Keith Novak]

I've definitely seen that. I rebuilt the original engine from my car the first season and followed some advice I read on the interweb about slowly bringing up the RPMs for 500 miles to break it in and it was bloody awful. Lots of time driving down back roads to places to apply torque and that motor was a DOG once I put it on the track. I recently pulled it apart and when compared to an engine I flogged hard from the get go, the easy break-in motor had shiny walls compared to the flogged motor that still had the dull cross-hatching. I now fully understand the term "glazed cylinders." I got the one with shiny walls deglazed, broke it in with the "flog it" method and it's a good little motor now. Now that fuel pressure regulators are legal, I figure I could stand to actually work on tuning the engine properly instead of "14 degrees of timing and call it good" so I'm wondering if I run my normal race oil on the dyno or put in break-in oil and why.

[Jim Boemler]

If your break-in period is on the dyno, I'd use dino (break-in) oil. You won't get your best dyno numbers (not because of the oil, but because the engine isn't broken in yet), but at least you'll get a better break-in. If the motor has already been through break-in (meaning it's run for over 15 minutes), then you might as well use the synthetic for your best numbers.

[Race Engineering]

The idea is to seat the rings as soon as possiable and it can take up on an hour at wide open throttle under a load.