I have a bunch of Polaris ATVs some newer, some older. I refuse to buy the Polaris AGL or Amsoil Gear case oil for 10-12 bucks a quart. I plan on using ATF fluid in there. Ive had them apart and rebuilt them. The transmission is a gearbox, with a heavy three link chain that basically drives the gears. What ATF would be the best choice? I have used the ATF +4 and thought it was the best. Its the same stuff Dodge spec's for their transfer case on 4x4 models, which is about the same. I have used the regular old Dextron/Mercon too without any noticeable noise or problems. The transmissions are simple and tough. The worse thing is gear oil, It causes drag and stretches the chain. I imagine motor oil would work too and the older Polaris's in the 90s even stated use 30Wt motor oil before Polaris came out with their own lubes. The transmissions are the same from 1990s to present. What is your opinion on the best ATF for this type of application?