FLYBOYJ
"THE GREAT GAZOO"
What I am referring to is fighter pilots abusing a single engine fighter during a dogfight and the report reads basically: describes running engine hard/abuse, using max power, maybe water injection, maybe over boosting, over revving etc, and without ever being hit by enemy fire "engine began throwing oil so I broke off and returned to base". So my 'engine throwing oil' question is aimed exclusively at that scenario. Why and where would it start throwing oil from because it was being abused in a combat scenario?
Well going back to your OP - the engine IS damaged ( be it "battle damage or not) at that point, again it could be a number pf items.