Wondering if all walker hydros take this Mobil 1- DTE 18M hydraulic oil? I have an older (1997) machine that that's what the caps say to use... However I'm not sure I've ever seen it sold around here. Walker dealer is about an hour away... Going t be running there to pick up so other parts in a few days, but I wondered if there was a different oil I could use? Dosn't the newer machines call for Mobil 1 synthetic 15W40 (or 50)? I just want to use what's best for them... They have over 1,000 hours on them now and going strong. Fluid was changed when I bought the machine about 450 hours ago... I'm sure it's "too soon" to worry about replacing the fluid, but it's winter and I'm bored, lol.