If it is a pink color then the Transmission cooler is bad in the radiator,
If it is oil for sure then the engine oil cooler that's in the radiator may be leaking oil into the radiator.
It would really help to know the year ,engine size and what you are working on. The above info may not pertain to your vehicle. Need to ask your question again with all information. THANK YOU NEUTZ.
RAD is an acronym for Regular Attribute Dodgers.
Blown head gasket!
Ich fahre Rad means I cycle
if you have antifreeze in the oil means you have a leaky head gasket.... or if your engine has the oil lines going to the rad like some s10s had get a pressure check on the rad could be leaking there as well
you have to remove the radiator,the cooler is integral to the rad,so the entire rad must be replacedh
Time for a new engine. Blown head gasket.
Possibly from the trany cooler located in the lower rad tank. This will destroy a trany in a short period of time if coolant gets in the trany
Partly cool
If it can be seen it will be on the dipstick when you first pull it out. Also check in the rad for traces of oil floating.
Your question lacks info. But, if the engine overheats at idle, and the rad is in top shape, and the thermostat is good, and you have a mix of at least 50/50 water/antifreeze, and the fan pulls good air, clutch fan I assume, then add an electric fan to the out side of the rad, to suck more air. If the engine overheats at higher speeds, then have the rad. checked, ( note that the fins on the rad might close at higher speeds preventing air flow ), Rad might be in need of a new core, thermostat might need to be replaced, OR, not enough fan cowling around the rad, and the fan pulls air from around the rad, and not through it. Sure hope this helps to solve the problem.
Your car is possibly burning oil which means you probably should have it checked by a mechanic. If your rings are bad, you could be burning it. Check to see if you're smoking or if there's an oily residue on the inside of your tailpipe. The engine may be burning the oil due to worn valve guide seals or piston rings or check your rad cap to see if there is a white foam or greasey oil on it.If you find oil in your rad the head gasket might be damaged or you could have a cracked block. please dont remove the rad cap unless the engine is cool!
Look for an access panel beneath the rad.