[Farmwithjunk]

With a fulltime mowing business, some of my mowers log more hours in a season than what most people accumulate in a lifetime. One mower in particular accumulated over 1400 hours last summer. It's still got the same oil in it again this year. I'd suggest checking the oil every so often. Make sure it's not leaking, or, check for contamination. SOME mower gearboxes tend to draw condensation. (Or leak water in around the gearbox vent. A good idea to watch for signs of moisture if you frequently pressure wash your mower) If you detect any signs of water contamination, use a siphon to draw out all the old oil and replace it. MOST mower gearboxes will require 90wt gear oil. (or a multi-weight gear oil)