If there's a better group to take this question, point me the way. If not, some of you guys have experience with hydraulics.
When I bought my Grasshopper commercial mower with a hydraulic drive 6 seasons ago, the dealer advised me to change the hydraulic oil at 5 years even though I wouldn't have 1000 hours on the machine. The lawn services rack up 1000 hours in a little over a year and change their hydraulic oil almost annually as a result. The manufacturer recommends changing the hydraulic oil at 1000 hours - which will be about 20 years at my useage. It requires synthetic oil and at $16 a quart it will cost about $64 to replace the oil, and another about $14 for the hydraulic oil filter.
I asked the dealer why to do that, and he said he believed that condensation in the oil tank would shorten the lifespan of the components. He said it was his theory that that's what caused some of the problems he's seen, but he stopped short of saying what specifically goes wrong. He felt that it was relatively inexpensive insurance compared to the cost of replacing components.
The machine now has 265 hours on it and is beginning its 6th season. The hydraulic oil has gone from clear to light tan and does not smell burnt. I can see some milky white oil droplets reminiscent of an oil-water mix clinging to the inner wall of the dispstick tube.
Anybody here with specific experience with Grasshopper mowers? Any experience with hydraulics and condensation causing problems over time? TIA
RWL