To start things off, welcome to OTT.
The engine oil is more than likely rated for 100 hrs oil drain and then says to change the filter and oil at 200 hrs. If I drain the oil at 100 hrs though I change the filter as well. But it should be changed at least once per year even if you don't put that many hrs on it because of the blow by that naturally contaminates the oil. If it has a real hyd filter it's probably rated to change the filter at 300 hrs, top the oil off and run it 300 more hrs and then change the hyd oil and filter. If it only has a screen filter for the hyd I believe the oil is only rated to run for 300 hrs and then change it all and clean the filter screen. A lot of people forget about the radiator when they do their PM. It should be drained and flushed at least every 2 yrs. Antifreeze will never freeze but it does however loose it's ability to disapate heat so it's important to keep it changed and a good 50/50 mix in it. Depending on the amount of dust you operate in be sure to keep a watch on your air filter. The dust precleaner will catch a lot of the debree and can be dumped out easily as you inspect the filter. I hope this makes sense and has helped you out.