What would cause this leak?
 

I have oil puddling on the 12a stamping on the front rotor. What would cause this leak?

Just rebuild it :D

there was a thread on this awhile ago the only thing i remeber is to check the tube on the side of your oil fill tube everyone else told that guy it was a dreaded dowl pin leak which means engine failure is soon but i have no clue on that maybe someone else will help

FWIW my 67K miles 80 RX has a similar problem on the OTHER side of the oil filler on that 12a mark. I have been told this is not that unusual. Just means cleaning the engine more often than I'd like. Mine is a very small "weeping", no big puddles... runs great
Stu Aull
80GS
Alaska

Mine runs fine also... Surprisingly. I treat it good most of the time, shift at 5k usually, but I do give it gas when the occasion calls for it. I pre-mix as a safety precaution even though my oil metering is still hooked up. It does not appear to be from the filler neck as I have read online, but maybe sometime I will rebuild it. It is just too damn rediculously expensive though.

A dowel pin leak does not mean imminent enginge failure. It just means the o-ring has shrunk and is leaking. Keep an eye on the oil level more frequently.

It does make a mess though. When I pulled my engine out to do the restoration, (it had only been in since summer), the entire drivers side of the undercoating was softened from the oil blowing under the car. Made that side much easier to remove the undercoating.

If left for leaking for too long, there is a chance that you could lose the underbody protection and accelerate rusting.