The mills I maintained ran on big Cat gensets. The last one was a 1000HP 3512. All maintenance was scheduled on fuel consumption, not hours or dates. Makes good sense when you think about it. In 1998 I started using a Honda GX4 water pump to transfer water to…well that is really another story. I rigged a 6 gallon tank from an old portable generator to let it run continuously. The motor runs at 1/4 throttle. A full tank would run it for about 6o hours. I change the oil every four tanks, figure 50 gallons because I usually don’t let it run it of fuel. That is about 200 hours of run time. I use the cheapest 10-30 syn-blend I can buy, usually from Walmart but I have used Amazon basic as well. I put another 70 gallons of fuel through it this year, so far. The motor seems a bit down on compression and has started to use a little oil. Still starts on the first pull. I wrote to Honda to share my experience, but never got a reply. By my cocktail napkin calculation using 600 hours a year I now have in the neighborhood of 15,600 hours on a splash lubricated single cylinder air cooled engine (though since it’s a water pump there may be some additional cooling). My point is that oil levels, and oil changes are what is important. If your piece of mind requires a particular brand of oil, then that is what you should use. I use T6 10-40 in all my diesel engines. Mobil 1 5-30 in my pickup. And the 10-30 syn-blend in my gas powered mowers. So far, so good.