Originally Posted by
jaka54
Hi!
I'm sorry!
You are right! Had not time enough to give a more elaborate answer.
Lean run is never very good for any engines. However it does take a bit of metal wear to get the blackness in the oil. So besides the lean setting I am sure there has to be some metal rubbing. Most likely from a loose muffler or some other parts internal.
OTOH, getting back to the OP regarding the shiny aluminum powder that is most likely a loose muffler since that is the closest aluminum part to the exhaust outlet. Or that could be from something outside of the engine. It is hard to tell without adequate information from the OP.