So, the story is that my '86 Coupe has been leaking oil and lately it's gotten a lot worse, but I've been unable to do any work on it. Initially I thought it was the driver-side camshaft seal. When adding oil yesterday I found the dreaded white goop on the oil filler cap. The engine is MPFI turbo and I know these have issues with the heads cracking, although mine has third generation heads. However, I think the oil may be leaking from the head gasket now. Any thoughts?

there's other causes for white under cap:
1.  short trips

2.  it's been like that for years and you never noticed

3.  intake manifold coolant ports bleeding into intake runners

 

are you adding coolant?  if it's leaking and mixing oil/coolant then you'll need to be adding coolant as well.

is it overheating?

 

a cam seal leak will be coming from behind the cam sprocket.

a head gasket leak will be coming from between the head and engine.

post a picture?

White goop on the cap can happen. White goop on the dipstick is a whole other thing.