Oil in intake manifold

88 5.3 V12

So a couple months ago I was getting a lot of oil in B bank air cleaner that i could tell was coming from pcv inlet, cleaned up OEM PCV, and that seemed to have fixed it.

But now several weeks later, I see a few drops of oil dripping from BOTH throttle bodies. The inlet from PCV is dry.

I have also noticed some of my spark plugs have oil on the threads, but no indication that the oil is in the combustion chamber, no fouling at all.

Could I have a leak somewhere that allows oil to get into intake manifold?

It’s not major, no blue smoke, and oil level is good.

All vacuum hoses going to intake manifold look dry.

Oil can come from the breather tube, on the front of the engine, as it also sees some vacuum above idle and the oil can find it’s way on both banks via the AAV and balance tube.
Check your B bank air filter box to see if there are any traces of oil.

If you see no external leaks above the spark plug there is no other way for the oil to get there except bad valve seals, worn piston rings or excessive blow-by. Oh yes, and head gasket…

Is the screen on the breather tube installed ?

Think vacuum and the direction of air flow that results.

My vote is from the air box or any opening before the throttle butterflys.


That’s probably not oil. It’s probably heavier fractions of fuel that has condensed out on the metal surfaces. Might be a result of too many short runs and not getting the car hot enough, I dunno.

sounds more and more like I NEED an ITU!