25 replies to this topic

[davew]

I have spouted off many times on here about using Mobil 1 street oil in a race car. Not gonna type it again. It's in my book and in the search function.

 

Trying to compare oil weights between brands is impossible. Pick the color bottle you like and adjust accordingly. Remember it is not the viscosity of new oil you worry about. It is the viscosity after it has been 300* and pounded by the forces of our 125hp motors. I learned a lot about oil from talking with the Gibbs guy at PRI many years ago. He told me the ball example. But I am a Redline guy. Never had an issue, so I stay with what I know. And I do mix weights to get the pressure I want. I also record oil pressure in the data and check regularly for any irregularities.

 

If you don't have an accurate gauge and don't care about the last 1/2 horsepower, I recommend the Schaeffer oil that I use in all my rental cars. I use the 20w-50 weight race oil. It is thick enough to provide excellent protection, yet does not rob horsepower like many other name brand oils do. I have seen a 9 horsepower change on the dyno, simply by changing oil.

 

Dave

[Richard Astacio]

You should have this discussion with your motor builder, he will have a recommendation about oil viscosity and target oil oressure.

 

Unfortunately the original motor that came with the car was not built by Sac....I left the original builder a few message when I first purchase the car and no return phone call.....

Since then SAC has built me a new motor and there is no issue...The original motor is now my back-up motor and was just wondering about the low oil pressures...

I guess I will experiment with oils on the back-up motor.....As far as reading Dave book, I guess I have to re-read it. 

 

The only reason why I started using Mobil 1 was because it was one of the sponsors for the runoffs last year..

[Jim Drago]

 

On the original motor I see 40+PSI when its cold and idling when I come to the pits after a race its about 10PSI-15PSI idling, goes up to 30+ if I rev the engine. 

 

What oil should I be using on that engine? I currently use 0-40 mobil 1 synthetic 

It is not so much 6500.. what you want to look at is what your oil pressure is at WOT after the car is at operating temps. The engine you mention was not built for longevity, but I have run some like that personally for years with no issue. I like to see 35+ psi at WOT when the car is at operating temps. From what you are saying, cold and idling doesnt tell me much. But I think you will be fine to run 10/40 or 20/50 or a combo of them. Try to get 37-40 psi at WOT, should be very doable from what you describe. 10-15 psi after a session and hot is low, but wouldnt neccessarily scare me either. I have a longacre warning light in all our cars that comes on when oil presure is under 20 psi. It comes on in every engine we build after a session at idle, very normal. We are usuablly 15-19 psi.

 

Jim

[Richard Astacio]

It is not so much 6500.. what you want to look at is what your oil pressure is at WOT after the car is at operating temps. The engine you mention was not built for longevity, but I have run some like that personally for years with no issue. I like to see 35+ psi at WOT when the car is at operating temps. From what you are saying, cold and idling doesnt tell me much. But I think you will be fine to run 10/40 or 20/50 or a combo of them. Try to get 37-40 psi at WOT, should be very doable from what you describe. 10-15 psi after a session and hot is low, but wouldnt neccessarily scare me either. I have a longacre warning light in all our cars that comes on when oil presure is under 20 psi. It comes on in every engine we build after a session at idle, very normal. We are usuablly 15-19 psi.

 

Jim

 

 

Thanks Jim, much appreciated, I will check my aim data. 

 

I set up my aim with several alarms, my dash lights up red after certain condition it also list the condition. 

 

I have low oil pressure, high coolant temp, low alternator amperage, 

[Wolfgang]

I'm surprised no one has mentioned sending samples out for testing. That can give you data on how "worn" the oil is after races, if it was overheated, the condition of the engine, if coolant is entering the oil, and lots more, for $20-25.

[davew]

Oil sample inspection can give you a lot of information. But most of it is not applicable to our situation. Get a good oil pressure gauge, know what it is telling you at speed, under load and HOT. Use good race oil of the proper weight so you have proper oil pressure (see mine and Jim's recomendations above). Most motors will last years in these cars if taken care of properly.