The heat thing is probably engineered into the newer engines, but I come from a time where I was trained to work on '70s era Detroits 3/53 - 12V/92TT, 250 -450v8 NA Cummins, V12 air cooled Continentals, and White turbo Multifuels They all but the White ran CRs of 22-24:1 Even my '84 Diesel...