So a few days ago, Ive noticed that there is some sludge building up behind my Oil pan & also around my front subframe. It could possibly be just an Oil drain plug gasket failure but then again there's a huge sluge going up. Also this never happenned till I have done my oil change & might have accidentally put an "oil filter" amount of extra engine oil. Ive read a few posts about "Leaking Rear Main Seal" & knock on wood hope thats not what's wrong with my car. But what could possibly be the effect of driving with a leaking rear main seal in the long run? Thanks!