oil in the antifreeze means what?

[sothpaw]

I am going to cheat a little and ask a tech. question about my
F-body car:

If I find the antifreeze is not clean, has some oil mixed in, what
could that mean? I had this happen months ago, assumed the oil change place(where I no longer go!) did it. Now, I am wondering if I should investigate more.

 

[alame]

hope it's just head gasket and not a cracked block

 

[Top]

Yep, blown head gasket. Get it fixed now before it really blows out bad and leaves you stranded on the side of the road overheated.

Also when you have the intake off pulls both heads and replace them both.

Good luck

 

[vader86]

head gasket

 

[oldace84]

Yep, I agree. vader beat me to the answer.
tony

 

[rrubel]

Dunno... if it's not a recurring problem, and no overheating is evident, then it could be nothing - or something else. I had dirty coolant on my Outback for years, but only recently replaced the head gaskets... some 100k miles after first noticing what looked like oil in the coolant and only after the car started overheating.

Supposedly it's more common to have coolant in the oil (turns all milky) than oil in the coolant with a cracked head gasket, according to the people I talked to when my Subaru was overheating.

I believe he's got an auto transmission; there could be a leak in the radiator lines that cool the trans fluid. If there's an oil cooler on the car, that too can leak and cause oil and coolant to mix.

And even if it LOOKS like oil, it could be anything. Best thing to do is have a hydrocarbon test run on the coolant and then have the coolant system pressure tested. And keep an eye on the temp gauge - if it does start to overheat, esp. when DRIVING as opposed to SITTING, pull off the road FAST. Down that path lies new heads...
[RICHR]

 

[Moonunit 451]

Good advice rrubel. Hydrocarbon test is quite reliable.

 

[sothpaw]

Thanks all,

I have an idea now that it's oil, as this V6 engine never used a drop and now it uses a noticable amount. Oil is either leaking or being used. Temps are always very cool, not even
a hint of overheating.

 

[Rich96c4ce]

If you are using that much oil, are you getting an overflowing coolant recovery bottle? Oil pressure into the coolant system will over pressurize it an blow coolant and the mixed-in oil into the bottle. Eventually, it will start to overflow because of all the oil you added to the coolant, inadvertently.

 

[Robertwav1]

How about changing out the anti-freeze? I don't know the history of the car. Like you said...you took it and had the oil changed...Anything could have happened there. I wouldn't condemn anything at this point. If stop leak is used in the rad it looks like oil. Lots of possibilities here. Investigate first and then head for the gaskets if necessary.

 

[sothpaw]

Don't know if stop leak was used, only had this car 1.5 year...

...but mechanic showed me coolant with oil in it over 4000 miles ago, and he flushed the system out. Afterwards, I saw no oil. But now I see it again. Plus, engine never used/leaked oil. Now, it has a slightly damaged oil pan/plug interface, but I used over a quart in 3000 miles, and another quart just now after 1200 miles.

No, I've never seen the antifreeze overflow.

I will reluctantly have this checked for the head gasket with an estimate to repair.

Still no sign of overheating this am.