I bought this at auction a few weeks ago and have no clue what hydraulic fluid is in the tranny. Changing that is on the list. Unfortunately the TSC brand you suggest is not available in W. PA anywhere. Will tey to find the Castrol suggested earlier. I am using an Amsoil diesel 10w30 synthetic that I use in my Sierra Duramax. I did pickup a new air filter today and will be changing that soon. I have changed the fuel filter and flow is not an issue thru the filter but I do need to run the hose the whole way to make sure it's not pinched off somewhere. That being said black smoke indicates unburnt fuel so I don't think fuel delivery to the pump is an issue. I used some Lucas diesel injector additive but will try seafoam. Good news is at least new injectors are available if needed. Thanks for all the input. I can solve gasoline issues but this is my 1st diesel tractor. Between it and the GMC I am learning a ton about diesels. All this emissions crap on the Sierra is driving me insane with codes so that has been my main focus lately. I will post an update when I get if figured out or need a new direction!!! Thanks again guys I truly appreciate all the input!!