In one of our Can-Am races back in the early '70s-- I forget which--, the weather was beastly hot. So hot, in fact, that after the race was over, some drivers had to be lifted from the cockpits and laid on the ground to recover from the heat. Bob Peckham, the owner & driver of a McLaren M8C, noted that by the end of the race, his gauges were showing a water temperature of 240F and oil temperature of 290F. Fortunately, everything stayed together and he finished.
We ran Valvoline oil, primarily because the Valvoline guys cruised the paddock garages, giving out cases of oil to any teams that wanted some. Sometimes they had ATF for the tow trucks, etc, too. I certainly don't recommend a 290F oil temperature but for the duration of the latter part of the 200 mile race, it did its job.
I guess I formed a loyalty to RC Cola for the same reason (other than I like it)-- they gave away ice-cold RC to all the racers.
Regards, Neil Tucson, AZ