The manual calls for diesel grade 10W-30 for both the engine oil and hydraulics. I've been using Rotella T5 and haven't had any problems. Do not use motor oil intended for gasoline engines! It doesn't have the right additives. As far as capacity goes, there are two different oil pans used on these machines depending on when they were made. You'll have to check your machines serial number against the specs for the machine to determine exactly how much oil to put in the engine.