JD claims that the hydros on the Z655 are "factory sealed" and require no maintenance. I don't buy into the no maintenance thing. I called my dealer and they concurred that no maintenance is required. I then called JD direct. They wouldn't give me the time of day. They said talk to your dealer. So then I called Tuff Torq, the manufacturer of the TZT7-M hydros. They said there are two drain plugs on each hydro and despite that the JD manual says to use 10W-30, they have found that 5W-50 SYNTHETIC is the best for those transmissions. Off to Walmart I go to get some 5W-50 Mobil 1