I'm not an A&P either - just a mechanical engineer. Opening the oil
cap immediately after shutdown & giving the breather pipe a shot of
compressed air should also clear out any crankcase airborne bad stuff.
I'm gonna try that next time I go & see what comes out. Tanis raised
this intriguing point in an earlier post some months back. It can't
hurt.

Around here (MN) we don't usually get that much engine corrosion damage
but I have seen what I now recognize as cold start damage as being more
common. I think one does have to be religious about starting only on
adequate preheat - especially if an engine has been sitting for
several days, and again especially if it is a Lycoming with the
camshaft on top.