A couple of things.
1. Check the oil in the mower gearbox and fill to correct level. Watch the deck for oil leaks from the gear box for a couple of mowings. Replace seals if it leaks. Replacing gears can be expensive.
2. Keep the radiator and screen clean at all times and get that whistle. Keep the proper coolant mixture, not a week solution or the freeze plugs can rust out in the block.
3. Make sure you read the right range on the dipstick. The same stick was used in two engines.
4. If you have problems with the belt tension pulley on the deck, there is a little nylon block that Kubota has to help keep it from drooping.
5. Make sure the bolts on the real wheel hubs are really tightened down, so the wedge hold the hub in place on the axle. If the bolts are not tight and you lose the pins through the axle, you risk losing a wheel.
6. Keep a clean fuel filter in and once and a while drain and clean the fuel tank.
7. Get a spare mower belt. They always break when the dealer is closed.
8. If the hydro fluid is clean, leave the darn stuff alone. I replaced it in my 30 year old
B7100 just once, and probably didn't need to do that.
9. Keep a collection of pins around for just about everything. They get lost like socks in the dryer.
9. Don't get An_l about this thing. Mine has spent 25 years outside, had one oil change, no engine rebuilds, no tranny rebuilds, no welds except one on the mid-mount deck. Starts every time, winter and summer. Sometime I think I would like it to stop doing what I bought it for (mowing),so I can get a new Zero Turn.