I have a 2016 Liberty Z that is serviced yearly. The hydraulic oil and filters have been changed every year by the dealer. The intervals are 67hr, 116hr, 170hr, and 210hr. This year I should be around 240hr. The manual states every 400hr or yearly. That seems like a large variation in hours since I only use for residential cutting. Is yearly still advisable, even though I'm well under a hundred hours a year. I would be comfortable with every other year. Opinions please. Thanks!