An engine thats been hit, damaged, and is loosing oil should not run like a pristine engine.
It should cough, sputter, choke, rattle and otherwise let you know its on its last legs. As oil levels drop power output should also drop. Till right before it seizes up its only putting out half the power it was before.
Think of it this way furball, you make a move on someone and manage to smoke his engine.
At this point would you prefer
A: he has undiminished power and can run home, land & exit safely
B" He loses power quickly, and is forced to ditch or die as a result, giving you the kill.
Anything that happens to a complicated system like an aircraft engine. Should have consequences, some of them severe. Even a fuel leak could concieveably cause sputtering, etc, lowering power & speed.