Annually is a good rule of thumb for engine oil, fuel and air filters, grease, service battery and battery box, wiper blades and cab filter. Typical 500 hour PM stuff.
Sample all the boxes to see how the lube is doing.
For justification, the Filter Manufacturers Council, says that air filters have a one year service life. They claim the cellulose starts breaking down at that point. (They are also in the biz of helping their members sell filters.)
interesting note, the FMC also says air filters have a three year shelf life. Donaldson says the same thing.
The reason I’m aware of this is because I had to keep an inventory of “ volcano” filters in stock for my Anchorage fleet of fuel tankers for a Municipal fuel contract. For when Mt. Redoubt gets angry.
The last time Mt.Redoubt blew up, within hours, air filters were sold out everywhere. Which reminds me, I’ve been lazy about keeping extra filters around for my stuff. Should stock up again. Between the weather, earthquakes, volcanoes, tsunamis, and wildlife, Alaska is constantly trying to kill me.