Ask an Oil Expert Part 2: Straight Talk on Oil for Track and Race Use

Illustrations by Sarah Young

Here's a link to part 1, where we discussed oil for street and autocross use. Have a classic? Here's a link to a article for those, too. 

Picture the spinning, rocking, whirling parts inside an engine. Now spin those same pieces to hundreds of thousands of revolutions per hour in a competition environment. And let’s do it …

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I like and take both of your magazines and have been waiting for these articles to answer several questions I have for 3 different vehicles: a stock 1967 230SL Mercedes, a highly modified 1970 Camaro - carburetted 383 that produces about 450HP and a 1987 300ZX race/track car. 

I am disappointed with this series of articles.  There really appear to be 2 or 3 standard answers; perhaps dictated by the respective corporate lawyers.  Answer 1: "follow the manufacturers recommendation".  Answer 2: "buy our specially formulated oil".  or "follow your engine builder's recommendation".  None of those 3 answers really helps me.  Or would cost me a lot more than solutions I think exist.  

Let's take each car and it's respective problem.  I would like to "improve" the oil in the Mercedes by using a newer synthetic but would also like the protection of ZDDP since there's no catalyst.  My question would be: what modern full synthetic should I use and how much ZDDP should I add per quart?  

The Camaro is much the same but a bit more of a mystery.  I have NO idea who built the engine and suspect that if I could find him/her their answer would be suspect and based only on their respective experience.  So, again the same question: what modern full synthetic should I use and how much ZDDP should I add?  I'm currently using a 10w-40 with a pint of ZDDP for the full change of 7 qts.

Last is the race car that competes in ChampCar endurance races.  The engine is required to be stock and the recent "Rockauto" rebuild was done by me, my son, and a local machine shop that honed the cylinders.  Clearances and rebuild components are stock or OEM replacements except for a reground cam.  Pan has some windage control but other than tuning it's stock and produced 175RWHP on the dyno/tuning run.  We would like to run an over-the-counter full synthetic and perhaps add some ZDDP  (we are curently running a rbeak-in oil).

All of these cars are DIY cars and we operate on tight budgets for each.  So, please don't tell me I need to buy $10-$15 per quart oil when I can get good modern full synthetic for less than 1/2 that price.  I suspect that many of your readers have similar challenges.  Perhaps your experts need to be off the record.

In reply to russelljones48 :

Agree 100%

Even when we were running the modified big block Chevy we didn't use any "race oil"   Just off the shelf Havoline.

Just a little info on the dyno we found that on our 500 ci engine  we made close to 35 extra hp with one quart less oil in the engine and also another 15 for  0 W 20 synthetic oil.  I would not recommend you race this way depending on what type of racing you do. Drag racing we can get away with it, but I would just look at what you see on the dyno as you run it up for your tune up.  One of the things we look for is oil temp and viscosity as it warms up, then as we run it through its paces with about 10 pulls. the test stand has gauges to check remotely from the control room and a video on the board to make sure we don't miss anything, when celebrating when we make more then we anticipated.

In reply to russelljones48 :

Sounds like you're off to a good start. Most of the information you're looking for is actually in the article but then you have to search for a few more things like go to driven oil and find their bearing clearance chart which is easier to find via Google. If we take your track car for example because it takes the most extreme use then probably a  5W40 mobil one full synthetic would be good. I has about a 3.5 HTHS and about a 13.9 viscosity and this would be good because your motor does not have tight bearing clearances as it's a 1970s block. The higher HTHS will protect it at elevated temperature ranges and the viscosity is thick enough for that block bearing clearance. Change it every six to eight track days and do some oil analysis and you should be fine. You didn't mention if that car had an oil temperature and pressure gauge but those would be excellent to have.  Most modern well engineered oils have plenty of additives so you probably don't need the ZDDP in the track car because changing the oil more frequently is more important than extra additives. Have fun with your track season in 2024

In reply to russelljones48 :

And then as a follow-up as to how to use the oil analysis let's say we take that 13.9 viscosity oil and you get the analysis returned and the viscosity is 9.9. That's kind of a large drop so you might want to move to a 10w40. If it drops to 11.5 and your oil temp runs around 260 and then the next time you analyze it it drops to 9.7 and your oil temps were 290 then maybe you need an oil cooler. And then on the very weird chance that you are evaporating oil and the viscosity returns as a 15.5 at 100° C then you need an oil cooler. Hope that helps. Have fun.

My corolla has been running anywhere from 240⁰-270⁰ on track with 0w20 (originally 0w16). I do wonder how thick of an oil I can get away with.

In reply to PlutoE210 :

For an M20-series engine, maybe 0w30 or 5w30 at most, these viscosities are already beyond the factory recommendation but people have run them without any problems.