6700 hydrostat problems

[gt275]

I was mowing today with my YT 6700 and it just quit pulling. I found the hydro stat reservoir was empty so I filled it with 10-40 motor oil. Nothing happens when I move the lever forward or reverse. I can shut off the engine, move the lever to reverse and it is hard to push. When I move it to forward, it is much easier to push. Air in the system? Any ideas much appreciated. Thanks

[cr250]

Most likely, keep adding and pushing back and forth,

[yamadog]

I would get that motor oil out and put 10 40 hydrostatic oil in there.  Motor oil will foam up in my experence

[casscounty]

      10W-30 motor oil is what is called for from the factory. It is the only thing I have ever used in my tractor that I have owned since new. It will not foam up.