Question about 1999 GMC Yukon
To answer your question directly; yes it can be fixed.
As far as causes, it could be a variety of things.
I would check the vehicle to see if there is an oil cooler which is either in the radiator or has lines in very close proximity to coolant lines. You may quickly find the source of your problem there.
It could be caused by other things such as a bad head gasket a cracked head, intake manifold or intake gaskets.
Odd cross contamination of fluids is something I have seen more and more in the past several years. For your problem I usually check for an oil cooler leak first, hoping to avoid the labor associated with head gaskets and cylinder heads. As far as a logical, understandable explaination goes for why a gasket or head might cause what you are experiencing, I offer the following.
My theory on your somewhat odd symptom of oil in your coolant without associated symptoms indicating a gasket failure is a result of having been puzzled myself on several occasions by what I consider the "new kind" of head gasket leaks. They seem to occur more often in cars that have aluminum heads on iron blocks and I have attributed that to the materials expanding, contracting, heating and cooling at different rates. They also seem to occur (in my experience) more often overhead camshaft motors, but I have not reasoned why that would be other than the ohc motors are more likely to also have iron blocks and aluminum heads. My best guess at a problem like you are having is head gasket or a cracked head because that is where all the flius involved are in close proximity to the others and where the conditions exist that could cause a part to fail which could result in cross contamination or leaks. The oddball single symptom is likely due to changing fluid pressures in your cooling system and engine oiling system. Starting cold, your engine coolant is not under pressure, but as soon as running you have oil pressure. If you have a leak or breach in a gasket or crack between pressurized oil passages and coolant passages you can get oil in your coolant. As the engine warms up, pressure greatly increases in the cooling system while it usually decreases slightly in the oiling system. If the pressure in the cooling system becomes greater than your oil pressure and there is a breach that allows the coolant into an oil galley you may end up with water in your oil as well. But it is possible that as the engine heats up, increasing coolant pressure, small leaks or crack close up as the metals and/or gaskets expand due to the heat keeping water from getting into the oil. If your oil cooler is ok, I suspect this is what you are experiencing.
Posted on Mar 24, 2016
A head gasket leak (blown head gasket) is highly likely. ($200)
Check your oil dipstick If it contains a milky fluid, that is water mixed with the oil. A sure sign of a blown head gasket.
Other symptoms of a blown head gasket include:
1. White smoke and excess water dripping out the tailpipe.
2. Overheatinmg engine
3. With radiator cap off, steam and water will erupt, sometimes violently.
Whichever tailpipe has the smoke is the side that the blown head gasket is located.
... sorry ...
Posted on Sep 12, 2009
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Posted on Jan 02, 2017
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