So do you use what the manufacturer suggests or do you use what you like? All manufacturers say to use their brand of oil when NONE of them have a refinery, so what makes theirs so much better then any other oil???

I use Mobil 1 in my vehicles. Motorcycles get Amsoil. Polaris' get Polaris oil, but thats only because the price of the two are comparable and its just easier to buy the oil change kit.
Polaris went to 2w-50,I guess, to make everone have to buy their oil since no one else makes that weight. I suppose the 0W-40 would work just as good.

Tried using Honda oil, but,like their quads, it breaks down prematurely!

i use shell rotella. i use it in the quads, rhino, lawn mower, lawn tractor, used it in motorcycles when i had them.

Hey Magoo here's a good write up on oils:

http://motorcycleinfo.calsci.com/Oils1.html

@Crash- been thinking about switching to the Rotella from Maxima. Do I have to worry about clutch slippage issues due to it not being rated for motorcycle motors?

I run Mobil 1 Full Synthetic in the quad. I run Yamalube in the sled just because the sled calls for a "low ash" oil and I cant find it anywhere so I just bite the bullet. As long as the oil meets the specifications that are in your manual, you will be fine.