Hi Guys/Gals,
I wouldn't be tempted to use automotive oil for the simple reason that your insurance may be void if you do. I have a couple of huge cylindrical air filters on my ag plane (Air Tractor 502) that cost upwards of $80 each. A friend of mine checked his automotive crossover book and ordered me two Wix filters for a substantial savings. I mentioned that to my IA and he said that if I ever crashed and the insurance co. found the Wix filters they could deny payment for the simple reason that the airplane was not certified with those filters.......go figure,