When I bot (sic) the plane the first thing I did was remove the freeze plug at the end of the crank to check for corrosion. The whole front of the crank (they are hollow on the snout for variable props) was filled with gray colored paste from the lead deposits.
That's because you don't have a constant-speed prop where the oil at the end of the crank is circulated...any dead end in the oil system will accumulate sludge.
The auto fuel STC is invalid in areas where they have the slightest amount of alcohol which is pretty near everywhere so those folks are stuck with 100LL. TCP is a good lead scavenger for low-compression 100LL users.
