My Dad loves using this stuff. He puts in in all his cars, boat, RV, even his lawnmower. I put some in a 95 Honda I had a while back. It was stolen one nite, but recovered the next day but with 200 more miles on it. Apparently the thermostat either broke or was damaged in all commotion, so while I was driving it home from the tow yard it got HOT! The temp gauge was pegged for about half the ride home, my mechanic said the head should have warped for sure. But everything was fine, no engine damage. Not sure if it was the Zmax that protected the engine or not, but it's cheap insurance like $35 I think.