F1technical.net

I am currently running a few saloon racing cars, both NA and TC from 2 to 300 bhp. I was using Castrol 10/60, then changed to Gulf Competition 15/50. I have never had any oil related problems, but I am thinking of moving to a 10/40. All races are about 15 min's long and the climate is Irish, yeh it rains sometimes. I would be grateful for any input.

John

Best thing to do is contact the petroleum company directly and get their feedback directly. Good at dispelling old wives tales about fuel and oil. Used to know a guy that worked on Shell's racing line of products... would have to see if I could dig up the contact info.