I don't know if there is a definitive answer for these questions. Some of the "uber" pro racers run clearances thru out their engines that would make most of us just shake our heads. In 74'/75', i watched Bill Jenkins dump close to 10 cans of BarsLeak in his radiator during a match race at Maryland International Raceway. I thought it was nuts, but super thin engine specs and a win at all cost mentality make some do crazy things...:D.
P.S. I should add that I didn't see the Grump actually put ten cans in his car. I saw him dump 2 in the trash can and didn't think much of it.....until I went over to throw out a cup and there were about ten in the can. Maybe he had just cleaned out his trailer...lol.