Just found my '96 Dodge Dakota Sport (original owner with 299,000 miles) coolant overflow tank near empty and radiator half a gallon low on coolant. Don't see any wet spots around any of the hoses and the fan is not wobbly. I found the dipstick oil level was above the full mark. No gray/white crud under the oil fill cap, but still concerned the coolant is transferring into the crankcase, I drained about a quart of oil. I will let the oil sit overnight in a clear plastic container to see if any water separates from the old crankcase oil (I assume the oil would float on top and the water would be found on the bottom layer).

I made a quick look underneath the chassis and found some damp spots here and there (not sure if caused by oil or coolant). Then it dawned on me, the problem may be one or more core/freeze plugs beginning to seep. If that is the case, I imagine trying to replace them with the engine still installed could turn out to me a nightmare. To be continued.

crankcase oil

 

If you had coolant in the oil, it wouldn't look like that. More chocolate milkshake consistency. The engine whips them together fairly well. Still, wouldn't hurt to change the oil. That's lookin' kinda dark.

How old are the hoses for the cooling system? Do you have A/C?? There is a short little hose that hides under that bracket, that will dry rot, and start seeping, right onto the top of the timing cover, where it pools, and then boils off. You will never see it hit the ground... (unless the hose starts leaking REALLY bad. ) Ask me how I learned about that one.

 

Another option is a blown head gasket .... coolant leaking into a cylinder and get burned without leaking on the ground.
The engine may run acceptably well, if you pull the plugs and check them ..... A very crude test .... if you pull a plug and it looks like it has been steam cleaned and brand new out of the box ... that cylinder is burning coolant.

 

Update: No change in the appearance of the oil after it sat overnight (rules out water in the oil for now). I removed the splash guards on both sides of the inner wheel wells and sprayed some degreaser followed by a water rinse. I was trying to get the core/freeze plugs located and cleaned. It appears one plug on each side is directly behind the motor mount which makes it more than a little difficult to inspect. Now I need to rent the coolant system pressure test equipment from the local AutoZone to see if we have any external leaks. By the way, my engine degreasing did not accomplish very much (this new biodegradable formula does next to nothing). Still not motivated to pull any spark plugs.