CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Oil in antifreeze

Have 2002 Chevrolet Malibu. Oil is getting into cooling system but antifreeze is not getting into the oil. Cracked block or manifold gasket gone bad or something else? What should I do, repair or replace car?

A breached head gasket (or two head gaskets–we don’t know whether the engine is an I-4- or a V-6) is much more likely than a cracked engine block. If it is a V-6, an intake manifold gasket problem is a real possibility, since this is a known issue with these GM V-6 engines.

Even if currently you only observe seepage of motor oil into the cooling system, the problem could easily morph into the more serious scenario of coolant getting into the crankcase. Right now, it is unlikely that there is any internal engine damage, but nobody can predict how long it will take before the breach in the manifold gasket or head gasket(s) worsens to the point where the oil is being diluted by coolant. Therefore, if you are going to do any repairs, I would suggest that you do them a.s.a.p.

As to whether you should repair or replace the car, we don’t know the overall mechanical and cosmetic condition of the car.

Has it been meticulously maintained, or have you been lax on maintenance?
Does it look showroom new, or does it look like it has gone through a war?
What is the theoretical book value of the car without any mechanical issues?
How much would your mechanic charge for head gasket or intake manifold gasket replacement?

We don’t know the answers to these questions from afar, but you can find out the answers fairly easily with a few phone calls to local mechanics and some use of internet sites such as Edmunds.com and/or Kelly Blue Book.

The 3.1L V-6 is a push rod engine and there is no oil pressure in the head. Only push rod oil enters the head. A failing head gasket on such an engine has no way of allowing oil to enter the cooling system, Does the engine have an oil cooler? If not, the original 2.8L engine that the 3.1L is based on had a big problem with cracks in the lifter galley that allowed oil into the water jacket. Of course GM took care of that design problem 30 years ago they thought. But I’m just supposing.

Are you sure it isn’t trans fluid instead of engine oil? If so, that’d point to a bad trans cooler in the radiator

How much “oil” do you see? There are other things in engine coolant that may look like engine oil. If it is just a glistening on top of the refill bottle do not worry much. If it looks like a quart of oil in the refill tank floating on the radiator water you waited too long to see a mechanic. Try a good coolant flush and wash the refill bottle out.

The intake manifold gaskets are prone to failure on this engine. However usually when the gasket fails you get coolant in the oil along with oil in the coolant. Nevertheless I would bet that’s the problem.

The 2002 Malibu 3.1 was part of the GM Dexcool settlement, unfortunately Oct. 2008 was the time limit to submit a claim under the suit.

http://www.dexcoolsettlement.com/notice.pdf

My 2000 Blazer was losing about a pint of coolant a month in 2003 with 44k miles. My trusted mechanic found a small amount of coolant in the oil after it was drained. He recommended that I have the intake manifold replaced immediately as even a small amount of coolant could displace the oil from the engine’s main bearings. He referred me to the dealer who verified his diagnosis and did the actual repair. The dealer did a “Goodwill” repair and split the cost 50/50. I’m still driving the Blazer today.

I don’t know if there was any oil in the Blazer’s coolant. Take the car to a trusted mechanic and get a proper diagnosis before proceeding. If it was me, I would drive the car as little as possible until it was repaired.

Ed B.

The OP did not say coolant in oil. But oil in coolant. Just so you are paying attention.