Send a sample of your oil to Blackstone Labs. They will give you a thorough analysis and make recommendations.

FWIW, here is my experience:
When we were racing a 1500 cc Sunbeam Alpine in the 1960's we had a problem near the end of the season keeping oil pressure up. We were running 40W Racing oil. After the first practice, we drained the oil and put in 50W. The oil pressure went up, but so did the oil temperature. Higher viscosity = more drag. After the second practice, we drained the oil and put the 40W back in and added a can of STP Oil Treatment (they were giving the stuff free to racers back then). The oil pressure stayed up, but the oil temperature went down. That made us firm believers in STP. After that, we would run practice with the oil from the previous weekend and drain it before the race and fill with new oil and the STP. We followed this same procedure the next two years with a 1100 cc AH Sprite. At the end of the season, the engine internals would be so coated and slippery with the STP that we could hardly pick parts up with our fingers.

I had Castrol Syntec 5W-50 plus STP in my car at the convention track day and it never gave any problems even though I have 342,000 miles on it.

Go do some research on oils... I came across Bob the oil guy on his forum and he got a degree studying oil lubricity and viscosity as well as wrenched on high end cars for years. Im not going to start to answer your question because there is enough info. out there to figure out for yourself what is best suited for you. Everyone has a right to their opinion and Im not trying to change anyones mind. Just letting you know whats out there.

Hey, I am just going on actual experience, not on what someone else told me. On our racecar, 50w ran hotter than 30w, and the oil pressure stayed the same. The only difference was much higher oil pressure at startup with 50w, but you shouldn't be racing like that anyway.

I'd rather have cooler oil, you?

Either way, I was hoping you'd back up your claim with some facts. #1 oil in Japan, and go do some research is useless information.

Looked up Bob's site, he's sponsored by Mobil 1, and I'm not entirely impressed with the site; just a couple of viscosity charts, animations and a forum full of circle track racers.

I believe that the only reason to use higher viscosity oil is when your engine bearing clearances require it.

Thicker oils fill the gap better than thinner oils. As long as there is enough pressure to "float" the crankshaft in it's bearings, the thinner oil you can use the better. Thinner oil means more HP due to less parasitic drag on the engine. Also, as rockwood pointed out, it's less work to pump it to where it needs to go.

Remember, the oil doesn't lube the crankshaft, it acts as a barrier layer to keep the crank from hitting the bearing (float).

Exactly. These aren't air-cooled VW motors. No need to clog up the oil passages with molasses.

The oil pressure went up, but so did the oil temperature.

Exactly what we noticed. Though, once at full tilt, the oil pressure was the same...

BTW, how much oil do you guys run in the crankcase?

The Eneos Oil statement is there motto so bother them about it, not me.

Like I said, all setups vary and one oil viscosity is not one for all. I agree with you on keeping oil temps down. I just figured since redXman was asking for comments, I gave him my 2 cents. Since he tracks only, with a 50w synthetic I assumed high rpm's would create lots of heat (which SR's dont like) to the point a 30w may just be consumed or burned over time.

I personally run a 30 weight in my SR, no problems so far but and I daily drive it and occasionally track it. I don't have problems with oil consumption untill I track it in hot weather in hot temperatures... then I change the oil and Im fine again. Glad you questioned me... its good to know ppl out there actually care.

Hey, I am just going on actual experience, not on what someone else told me. On our racecar, 50w ran hotter than 30w, and the oil pressure stayed the same. The only difference was much higher oil pressure at startup with 50w, but you shouldn't be racing like that anyway.

I'd rather have cooler oil, you?

Either way, I was hoping you'd back up your claim with some facts. #1 oil in Japan, and go do some research is useless information.

Looked up Bob's site, he's sponsored by Mobil 1, and I'm not entirely impressed with the site; just a couple of viscosity charts, animations and a forum full of circle track racers.



Exactly. These aren't air-cooled VW motors. No need to clog up the oil passages with molasses.



Exactly what we noticed. Though, once at full tilt, the oil pressure was the same...

BTW, how much oil do you guys run in the crankcase?

2.5k miles or 60 running hours. I work for Stewart-Warner / Alemite. I get oil free :)!

2.5k miles or 60 running hours. I work for Stewart-Warner / Alemite. I get oil free :)!

shoot... no need to worry.:D

Before every event. I worry way too much.

no matter what every 2500 miles only cause i drive hard every time i drive my sr20 an use castrol 10-30 and nissan filters ONLY

I use Mobil 1 10W30 at the beginning of the season. I might change it at the middle of the season this year. The car seems to burn / consume a little when racing in hot weather. I always check it and keep it near full on the dipstick. My motor is stock internally and has 110,000 miles on it or somewhere near that. Mileage on the motor, miles during season, and how radical the motor is are all variables to recognize. I considered going with the thicker oil last time but agree with the thicker oil raising the temp and increasing drag and thus reducing Hp. I have no data to support that belief though... Part of the discussion that may have been overlooked here is what oil filter is used. That would be a variable unless everyone is using the same filter. I use the Mobil 1 filter.