My L4701 just went over 200 hrs. Did the initial 50 hr. oil and filter change. I used premium oil and Kubota filter. The owner's manual says to change oil every 400 hrs. It has been 15 months since the original 50 hr. oil change. Oil still looks okay, darker, but not coal black from soot. Note to those engineer/techno types - Not going to send it out to get it analyzed, cheaper and easier to just change it. My question to folks is, at current usage rate it will be 3+ years on an oil change. Seems like a long time, maybe too long. Tractor sits a lot lately, due to ongoing health issues. (Getting old sucks!) Just wondering what others are doing in similar situations. I'm leaning towards changing it sooner rather than later. Don't figure it would hurt anything. Oil and filter are not cheap, but when compared to cost of tractor or engine re-build, dirt cheap!!