I want to know what is the reason for oil being in the water system of my four cylinder ford pickup truck?

I want to know what is the reason for oil being in the water system of my four cylinder ford pickup truck?

If your p/u has an automatic transmission, then there's a cooler for the tranny fluid in one of the side tanks of the radiator, usually the driver's side. IF the tubing inside the radiator that carries the tranny fluid rusts thru, that will do it. Next possibility is a bad head gasket.

Leaking transmission cooler or head gasket. Those are your only two options

Cracked head or block

Leaky head gasket.

Bad head gasket, warped or cracked head.

Blown head gasket, cracked head and/or cracked block. The 22re is a bit prone to erosion in the head where the coolant passes from the block to it. I had done a head gasket on a 90 toyota pick up and the issue was still there. I replaced the head and it solved the issue.