Car is 99 Z28 104,000 miles

-Runs great
-Does not smoke
-Does not get hot
-Oil on dipstick is perfectly clear

Took car in for oil change last week and guy showed me the Oil Cap. There was a white/greenish milky residue on the inside. So he doesnt know what the problem is and recommends an Engine Flush. So we do that and today I checked the cap again , looks the same.

The water pump has a leak (small) on the top/base, no clue if this is somehow related.

Can anyone tell me what this is ? I read that it could possibly be "condensation" but Im thinking something else is going on

 

I would say get the water pump leak fixed -- easy to do yourself -- probably the gasket...

Also flush your coolant if you haven't in a while -- install the Prestone flush kit...

 

So its possible the water pump leak is causing this problem with the oil cap ?

 

No, the water pump is not causing the problem, although you "may" have some coolant leaking into your oil someplace else. After letting the car set for a while and its cool, pull the oil drain plug and drain about a quart of oil into a clear container. Let it settle for a little bit and if you have coolant in your oil it'll be easy to see as oil and water will separate and water is heavier than oil. If all you have is good ol' oil I'd say you have nothing to worry about and that bit of milky crap on your cap is probably condensation. If you do have coolant in your oil that's when the real fun will start.

 

I'm not going to read your entire post, becuase I dont have to. Milky residue in an oil cap is a blown head gasket.

 

Not always

 

Not always stig. Many times it's just condensation. I would follow the advice above and drain a little oil into a clear jug, let it settle and go from there.

 

Changed out PCV valve and connecting hoses

Valve was completely clogged

 

I know its not always, but it was my hypothisis and no one had said it yet.

 

i agree with some of the guys you have a blown head gasket thats forsure....