What happened after you washed it out?did it come back thick and creamy or was it ok?.

 

You know, Blown Head Gasket sounds like the problem exactly, I would like to throw in another possiblility, however, it probably isnt the problem, but you never know. If you dont change your coolant it becomes acidic. The more acidic something is, the more it conducts electricity. It can cause rust build-up and even make rubber parts melt. Sometimes, but not most of the time, the build-up of a black tar substance is actually rubber!!!! It can come from seals in the cooloing system and rubber components. Now if your head gasket is gone, a couple people are right in the previous posts. Oil doesnt mix with coolant until its churned up and emulsifies. But put this together.......If you start your engine, your oil pump soaks up coolant to use as a lubricant instead of oil (oil floats on top), this is not desirable for this is whats going to lubricate your main bearings, connecting rod bearings, and pretty much your whole engine. Everytime you start your car your killing it more and more. When the oil and coolant emulsifies, then your pretty much doing the same thing, just not as intense. But still, remember that point.