The oil in question is a residue, not cosmetically nice but acceptable. The overheating you cite, if sever, could have killed the piston rings' temper and so created an oil burning engine with a lot of compression loss that causes "blow by" into the crankcase. Hopefully that's not the case. Suggest you keep a log to determine exactly how much oil must be added after X,XXX miles for THAT's the im****tant test. -- © 2008 T.G.Lambach. Publication in any form requires prior written permission.
