What can be the cause for having oil in engine coolant ('96 Buick Century)?

Question

I test-drove a '96 Buick Century (3.1L engine) today, and it seemed like a pretty good car. Drove nice, no shaking, noises or smells. Seemed like a good car till I looked under the hood. It looked fine at first, until I looked in the coolant reservoir, and saw it had oil in it. I thought it might be from a blown head gasket, but there isn't any coolant in the oil. The radiator looks like it's new so maybe they changed a bad radiator, but didn't flush the cooling system? Does anybody know what the cause may be?

Answer 1

GM 60-degree 3.1 V6 says it all.  These engines have a chronic problem with coolant and/or oil leaks caused by a faulty Intake Manifold Gasket.  Every one of these engines leaks eventually which can cause the fluids to mix.  There was even a class-action lawsuit on this matter that was recently settled.  This is most likely the problem.

I recommend replacing the existing gasket with Dorman Part #615-205.  This is much improved over the original GM design and the kit is extremely complete.

Answer 2

usually a indication of a cracked head,or bad head gasket

Answer 3

The Intake manifold is leaking coolant into the oil, This is an easy fix if you know anything about cars.

Answer 4

Very possibly a cracked block, I would walk away.

Answer 5

It still might be head gaskets. Oil pressure is at 40 p.s.i and coolant is only 15 p.s.i. have a pressure check done on the coolant with the motor off and see if you loose pressure

Answer 6

You need to find out for sure what it is. You can get brown gunk in the radiator by mixing green and orange antifreeze. You can also have transmission fluid in there from a bad tranny cooler in the radiator.

You don't always have water in the oil when you have a blown head gasket, so that could be the problem.

Answer 7

If the radiator is new, then the reserve tank should have been cleaned out too.  What looks like oil in the reserve tank a lot of times is filth.

Answer 8

Probably didn't thoroughly clean the resevoir when they changed the radiator.