[Old182]

My recollection of painting the inside of engines originated in the 1960s with racers. The coating sealed any sand from casting or blasting (keeping it away from bearings) and also helped the oil drain back into the pan quicker, presumably keeping the oil cooler. I always figured it made sense to do this on engines that ran hot and needed extra protection from hard, small materials like sand or iron - like race engines, and as mentioned, aircraft engines. I agree with most here: It probably doesn't hurt, but why bother fixing a problem that doesn't exist on a street engine? Regarding Eastwood, they need to be visited by the FTC for selling other products that fix problems that don't exist also - bummer - I used to have faith in them.