As Tone mentioned could likely be head gasket, as if someone looked at it and there was oil in the water it would be pretty obvious (looks like creamered coffee). Most shops have "sniffers" that can detect exhaust gasses in the coolant, providing a positive ID of your issue. They can also perform a leak-down test which is also simple and inexpensive (you can do it yourself even for less than $50) providing additional info.



You should take a look at your fan thermo-clutch to make sure it's activating properly as well, since you need to address the cause of the overheating or else any repairs will be moot.

Hope that helps, keep us informed of your progress!