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Originally Posted by DennyM
Just want to add that while you're out there competing to win, you're already a winner in the eyes of a 12 year old and an 8 year old.  |
I agree.
Your coolant temp issues would have me concerned as well.
As for the oil question, my personal thumb rule is to use the AMSOIL Series 2000 20w50 if you are seeing track oil temps over about 270F or so (or if your engine has been modified and your builder recommends a higher viscosity oil). I ran this oil throughout the 2004 season while racing in the hot Memphis summers.
However, this summer in slightly cooler temps I was running the AMSOIL SAE Synthetic High Performance 10w40 which has a High Temp High Shear rating of 4.3. For comparison, the Mobil 1 Extended Performance 15w50 has a HTHS rating of 4.43 so with the AMSOIL HP 10w40 you are getting nearly as much high temp protection but less internal friction which may free up a few HP.
I had recently discovered the AMSOIL SAE 10w40 Synthetic Marine Motor Oil when a customer asked me what he should be running in his inboard/outboard small block Chevy boat. This marine oil is formulated with very high levels of anti-wear additives to meet the continous high load requirements of a marine engine and has an HTHS rating of 4.6, which is higher than the 15w50 Mobil 1 EP. It does meet API SL standards which was the standard until 2001 when the API started putting lower limits on the ZDDP antiwear additives in automobile oils. I had actually ordered two cases of this and was going to change it out after my Saturday race on June 3rd in preps for the Sunday race. Turned out I didn't need it.
Here's my rough guide:
Oil temp over 270F:
AMSOIL Series 2000 20w50
Oil temp 240-270F:
AMSOIL SAE Synthetic High Performance 10w40 or
AMSOIL SAE 10w40 Synthetic Marine Motor Oil
Oil temp under 240F:
AMSOIL Series 2000 0w30
Congrats on your personal best time there and finishing in the rain, always a good thing. Good luck at Road America.
