Yah, my old cap I took off when I redid the manifold gaskets and fuel regulator had the same thing. I thought it was condensation which might have been from a crack in the cap somewhere.
I replaced the cap and checked it today and it is infact oil.

The distributor was replaced when I built the engine.. Its a PROCOMP and after seeing this i'm thinking it's junk??

Opinions?

This is the buildup after 5 days...

 

I had an older HEI dizzy that did the same thing - there's a seal down in it somewhere - but I didn't see where it was worth the trouble, when a brand new Accel brown cap dizzy can be had for $125 at Autozone, so I just got a new one of those, and it works fine - also came with adjusting springs and other goodies if I ever figure out tuning to that degree - but it does NOT come with the coil.

 

What kind of crankcase breathing system do you have? and what is the max RPM that you run to. Too much crankcase pressure in high RPM can force oil up your shaft also.

 

Stock PCV system.
6,000rpm.

 

Might want to try an open system W/breather caps on the valve covers.