There are benefits to using full-synthetic oils, but using any oil that has the rating your manufacturer states must be used will ensure the engine is safe.
I don't use the spendy stuff on sleds unless they have power valves. On the non power valve sleds, I use the cheap stuff from Wally World at 10 bucks a gallon. It protects just fine. It will protect a power valve engine as well, but you may have to clean the valves more frequently.
2007 RMK 700, 2008 RMK 600, 1995 AC Prowler 2-up, 1980? AC Cheetah
From what I've noticed ;;;;; rings and pistons seem to last 2000 to2800 more miles with synthetic. No difference in melt downs or crankseal fails..So it works out to be the same, pay for parts or pay for oil.
For mine, amsoil worked better than polaris gold syn. for power valve carbon. I switched to syn. ten years ago, to reduce the smoke trail and ride in -40 weather.