why is oil getting into the radiator water? Do I need head gaskets? on 2000 Ford F-350 Super Duty

280k miles. I can drive about 40 miles then will hardly run. After shutting it off & restarting it runs okay again.

2 answers
Is the transmission oil cooler in the engine radiator could it be leaking internally? Perhaps post your question on a Ford truck specific website maybe someone knows a common problem.
could be your oil cooler above your oil filter. they tend to go bad and leak.its a 2 pc assembly. one bolts to the blk above motor mount and the other pc attaches to that.