I have a 94 s-10 blazer. It has the 4.3L vortec. I have already replaced the fuel lines to the CPI and I am replacing the regulator tomorrow. I noticed that in the port for the EGR and on top of the manifold next to the head there is oil. It is coming from between the upper plenum and the throttle body. Question is how is it getting there? I have already checked the PCV valve and hose and the bottom of the PCV has some oil on it but that is normil and the tube going to the throttle body is dry and the PCV is functioning properly. Could this possibly be the manifold gasket? I have had a lot of anoyances with this motor but nothing drastic and I have 247000 mi on it with no major repairs so I am not complaing but oil leaking could cause all kinds of problems. Someone Please help.

 

Are you sure its oil and not just gunky carbon build up?
Oil shouldn't be to sticky the carbon will be.
Do you use (burn) alot of oil? if so is it possible that oil is getting past the exhaust valves and into the exhaust system and some is being pulled back thru the EGR?