I've been running Kubota ZD's for 15 years now. (Great machines) I've had excellent results by pumping 2-3 squirts of grease into the spindles and u-joints at every fuel up. (8-10hrs)
It has worked well for me. Never a failure or problem and keeps new grease at the bearing all the time.
The u-joints on the drive shaft that goes between the engine and hydro unit are the hard ones to get to and get neglected most often, so don't forget them.
Also, of you mow around wire fences, (ie. farms) take the clevis pin out of the front casters on the deck and replace them with double nut bolts or lock tite the nuts. The fence wire will flip the clevis open and the caster goes into the blades without you knowing. The sound of the caster being ground up isn't nice, and definitely raises your pucker factor. I speak from experience. (more than once, because once just wasn't enough!)
