This may be a dumb question, but why would oil leak from the intake? Shouldn't there only be air and fuel in this area? I know this is a common problem on these cars and it seems mine has it. But when I was telling someone at work about it he asked this question and I could not come up with an answer....

Bill
1995 Z28

 

The bottom of the intake seals the lifter valley were lots of oil gets squirted around. The intake manifolds don't leak, the leaking is at the seal between the intake and the block.

The orange rtv in this pic is where it's leaking at in the back.

Letter A in the picture

 

It leaks becasue the guy at the factory was drinking the night before he had to come into work and assemble your engine.

 

It leaks because of the EGR that feeds into the back of it. Notice how its always the rear seal that starts to leak? Thats because there are incredibly hot exhaust gases being pushed into the rear of the intake. Over time this excessive heating, and cooling (when the engine is off) causes the gasket to break down eventually leading to the dreaded INTAKE OIL LEAK! Really where it leaks commonly there is no gasket, there is only gaskets on the intake runners. That particular part just has RTV gasket sealant there.

And like luckyou03 said, the oil comes from the lifter valley.

- Z28WannaB