Oil & Fuel John Deere 850 has hydraulic oil in engine oil

[norms850]

I have a John Deere 850 4wd tractor that I was using yesterday when all of a sudden the oil overflow hose started to leak oil. When I pulled out the dipstick , oil came dripping out. I appears to have hydraulic oil mixed in with the oil. How would the hydraulic oil get into the engine. what things should I look for.

 

[Zebrafive]

Your hydraulic pump must be leaking into the engine. I think it's bolted to the front engine timing cover.