When you check the oil in your engine and it looks like someone poured a chocolate milkshake in your engine, then it is safe to say that there is water in the engine oil. When most people see water in the engine oil, they immediately think about a blown head gasket. Although it is true that when a head gasket leaks, it can cause water to mix with the engine oil, it is not always the cause. Depending on the design of the engine water being mixed with the oil can be caused by something as simple as a leaking intake manifold gasket.
If the engine in your vehicle is a “V” style engine with the intake manifolds that seal to the block, you should be aware that the oil gallery is directly underneath the intake manifold. You should also be aware that coolant circulates through the front and rear ports on the intake manifold, to provide cooling to the cylinder heads. Of course, there is a gasket between the cylinder head, and the intake manifold. Some ports hold vacuum to supply air to the cylinders, and some are under pressure because they are part of the engine’s cooling system. There are also seals between the intake manifold and the block, but they are not important for this situation.
Anyways, in the name of being environmentally friendly there was a new type of antifreeze developed that was safe for animals to lick up without being poisoned. This is because the new coolant is made out of food byproducts. Not bad, huh? Very bad idea though. Food has bacteria in it, and the bacteria eat everything it comes into contact with. These bacteria eat through the weakest point first, and that is the intake manifold water jacket gasket. Once that happens, you have hot pressurized water spraying the inside of your engine. Sure there are tablets you can add to your cooling system with this kind of antifreeze that will protect the surfaces on the inside of your engine’s cooling system from the bacteria, but they are not generally available to the public, and they are not something that everybody knows about. The auto manufacturers sure pulled a smooth one on that, but who is going to argue and say that being environmentally conscious is a bad thing?
Of course, if your engine is not the “V” style engine, then you will be removing the cylinder head from the engine to find out what happened to make water and oil get mixed. To sum it up, if water is mixing with the oil in your car’s engine then there is a leak in the water jacket of the engine that is letting the water spray into the crankcase. Other things that will cause this to happen, besides leaking intake gaskets (on v style engines) and head gaskets, are cracked engine castings, like the intake manifold, cylinder head, or even the engine block. Normally if the engine block gets a crack that allows water and oil to mix, it is in a cylinder wall.
Now you have a better idea of what to look for, when water and oil start mixing and your engine oil looks like chocolate milk. Just because water and oil are mixing, it does not always mean that you have to rip the heads off. On some engines it can be fixed with a $15 gasket, and about 1 hour worth of work. It should only take an hour if you are also the only one who is watching the barbecue pit, with having to wash your hands every time you tend to it, and all that.