Oil in the water of a radiator?

So I have an 87 Toyota Tercel Wagon with the A3 engine. It's just had a water pump done. We just bought it a few weeks ago because one cylinder wasn't firing (it was just a bad spark plug) but it does burn oil. For some reason there is oil in the radiator water. Does anyone have any idea as to why it would be in there? Give me all of them. (The timing belt also had oil on it if that helps.)Oil in the water of a radiator?
the oil in the radiator is probably came from the head gasket, its leaking from the gasket, youll notice that your temperature is going up, or otherwise not. and the oil from the spark plug, thats your valve seal, its already worn out, youll notice a white smoke on your tail pipe. the oil in the belt is from a leaking seals.Oil in the water of a radiator?
Sounds like you got a bad engine. Oil is getting into the cooling system either through a blown head gasket (fixable) or because there is a crack in the cylinder block or head (engine is junk). From your brief outline of the condition of the engine I think your car needs a new motor.
Sounds like your head gasket is either blown or is about to be. If your car starts running really hot really quick or you can't keep oil, you need to take it in, or it may even be time for another car. Head gaskets are expensive to repair, can sometimes run well over $1,000. Best to put that towards another car. Good luck!