Why is oil going into my radiator ford 4.0l?

Why is oil going into my radiator ford 4.0l? - 1

A blown head or timing cover gasket can cause it. Both oil and water present there and a bad gasket can cause it to mix. It also could be trans fluid rather than oil. The bottom portion of the radiator is a transmission heat exchanger. If it fails transmission fluid can mix with the coolant.

That may be ATF leaking from the cooler that is mounted inside the radiator. Get it diagnosed immediately! That can ruin the transmission fast. If you need to replace the radiator I'd get the ATF and tranny filter replace right away too.