When I met Chumma I asked him about the problems some people had with overfilling the crankcase oil. He has been inside many RE engines. He said that there is about 6-8 oz that does not drain when you pull the drain plug. It remains trapped inside the engine. Then when you put in the "correct" amount, half way up the sight glass, everything looks OK. When you start the engine, that that trapped oil joins what you just put in. Now your engine is overfilled. Soon your air cleaner box will be filled. I start with 1.5 quarts, run the engine for a bit and check the level. Adjust as necessary. When I expressed my concern about keeping some dirty oil with my nice clean stuff he said it was not enough to matter.