I use the synthetic T6 in everything at the farm except for the little 2 strokes. I just buy the 5 gallon drums from the auto stores when they are on sale. I go by hours. Some get used 50 hours a years, some 100 and some less. I used to change oil and filter every other year and realized I was just draining out money and time. When was the last time you saw an oil related problem? How many POS minivans have you seen out there that probably haven't had the oil changed in years that drive along just fine with no smoke. I see Massey's in Africa with 5000 hours on them and still have the factory painted filters. With the oils these days, especially synthetic, and the production specifics used in the engines the factory noted intervals for engine oil/filter are more than adequate for me.