You guys can use aviation grade parts as well. ?Positech Oil coolers available through Aircraft Spruce are a good buy. ?$165 will get you a good aviation quality oil cooler that will address high oil temp issues. ?I installed one of the Positech coolers on my SuperCub clone. ?I make a lot more heat and have a lot less air flow to work with, but it keeps the oil temps on my O-320 nice and cool. ?I would think the oil cooler intended for either the O-200 or a Rotax would work quite well on a VW.
-Jeff Scott Los Alamos, NM
