I had to google that one a bit. Most hydro/transaxle fluids are more like 20w50, BUT, there's plenty of ~30W specs out there also, should be fine.We will be using Mobil 1 5w30 in the trans axel
You can buy a pre-cleaner oil , better than WD40 , it is quite sticky and definitely traps the dust and debris"For a Kawasaki engine in the Cub Cadet ZTX5 54 zero-turn mower, the recommended engine oil type is 10W-30 SAE Premium 4-Cycle Engine Oil."
I'd prefer Castrol or Valvoline.
Manual says first change at 25 hours then every 100 hours after that. Changing more frequently for extreme use or engine longevity certainly would prolong life as well as keeping a clean air filter on it. I wash the foam pre-filter, dry it and spray a little WD-40 on it. It seems to catch more dust/dirt that way.