Oil in my Radiator?

I have a 1992 ford ranger 4 cyl standard tran. The radiator has this black gunky stuffin it and when i take the radiator cap off it is pretty thick on the cap. What could this be?Oil in my Radiator?
rust or heavy lime i recommend doing a radiator rinse and drain if persists you could have a big prob.Oil in my Radiator?
Good guess.......
Possibly just a build up of junk,or a more seriuos problem such as a cracked head or block.The only way oil can get into the cooling system is if there is crack in between an oil gallery and a coolant jacket.One suggestion would be to do a complete coolant flush with a caustic chemical to remove all of this black stuff and any rust and corrosion,refill system with a 50/50 mix of water nad antifreeze,drive it ans see what happens.
It sounds like you might have a crack in your engine block, allowing oil into your coolant. It could also be a head or head gasket leak as well. Check for excessive steam like exhaust which would indicate a cracked head gasket or coolant getting into cylinders or check if you have any coolant in your oil. If you do, do not run the engine or you will destroy your engine. In any case you will likely end up changing the head gasket.
Many times people put regular tap water in their radiator and this is unacceptable because of the lime content in it! The lime builds up on the cool spots of your cooling system, which is the radiator and the thermostat and then the thermostat freezes up and it over heats the motor and blows the head gasket and this is where you get oil in the radiator! Use only radiator fluid and distilled water in your radiator! Oh and by the way change your head gasket too!
You either have a cracked head or a blown head gasket.
it is not oil ,but dirt. what need to do is have a deep flush done
COULD BE EITHER THE( OLD) ANTIFREEZE/RESIDUE THAT YOU THINK TO BE ';OIL';---BUT, COULD ACTUALLY BE ';OIL'; DUE TO CRACKED BLOCK,OR DEFECTIVE GAsket---suggest that you see a qualified mechanic FOR A MORE DEFINITIVE DIAGNOSIS.
If its also in your overflow bottle/spare resivoir it could very well be a head gasket.But give it a flush first as they can get lime depositry from chem reaction
Take it to a good local auto shop.Have them pressure test the cooling system.That will show if you have a head gasket problem.If the system has good pressure have them flush the system install new coolant and your good to go.Also some times you have a oil cooler hooked into the radiator that tank could be leaking and putting oil in the coolant have the shop check that for you.Hope all works out.