Tractor Repair: Diesel fuel in the oil, leak fuel, fuel pumps

Question
I have a John Deere 8300 tractor that I suddenly found diesel fuel in the oil.  It has plenty of power and runs and starts good.  Why did this happen?

Answer
You need to take out the injectors and have them checked pronto. That is the only thing that can be  adding the fuel to the oil by washing down the cylinders. Is the tractor been smoking lately?
I have Not seen any fuel pumps leak fuel that way but I have seen several sets of Injectors do that very thing. This is very serious problem that you need to deal with before you wash your cylinders or bearings.