I've been toying with the idea of running it in my and the wife's Yamaha Grizzly 660 but haven't done it yet. I changed it with Rotella T6 and Fram Ultra last and haven't put enough hours on it yet to justify changing it! Lol
But honestly, I'd have no qualms about using it as it shows great results in PCMO and HDEO applications here. The problem with my situation is there's no Walmart nearby within 100 miles so I can only get it if I'm on a trip out of town and happen to come by a WM.
And modern ATV engines are more efficient and tighter tolerance than ever. They're quite easy on oil as long as you keep your air filter clean which is even more important here than anything else as they're obviously exposed to way more dust/mud than cars by a long shot! I use M1 in my 400EX because it's available here and does well in the extreme heat air cooled engines build up, especially in the dunes on a hot summer day climbing a 100' wall of sand with heavy paddle tires and a 200lb rider aboard. But I believe the ST would do well in it also, it's just the M1 I can get right here locally and can't with ST.
I use the 10w-40 variation in my commuter scooter for the last 300 miles (Alot on a scooter) and its ok. I noticed the enigne isnt a quiet as it was with Castrol power or valvoline and I'll probbaly go back to that. No Shared Sump
Is there a UOA on the ATV oil yet? Would love to know how it compares to t6 5w40 and rotella white bottle 15w40.
I currently use t6 in my crf450r and 250r, regular rotella 15w40 in my sons klx air cooled bike and other OPE. (gensets,mower etc)
I would be more tempted if they sold it in a gallon size. Same as others, I can use t4 or t6 for the two Honda Ranchers, Small Tractor, and riding mower. Makes it really simple to use the same oil for three different things.
Here is what I've been using in my 2014 Honda Rancher 420 4x4 and it seems to work very well. The engine is definitely quieter than when I was using Rotella T6 5W-40 and even the Honda fully synthetic 10W-30 motorcycle oil.