I have a 2010 RZR S that is snorkeled with separate vent tubes ran up the roll cage for the trans and transfer case. It has been running great up until the last ride when I run the RZR hard, transmission fluid starts making it's way up the vent tube. I'm not sure yet if it's coming from the trans or the transfer case, as both use the same transmission fluid. The vent tube is all the way to the top of the cage, and at one point the fluid was coming out of the vent. If I back off the throttle for a while or stop and let the engine cool down the fluid goes back down. Has anybody ever seen this happen or have any idea what could be causing this?

First things I could think of if you are using a different fluid than what is called for,it could be foaming up or even if you are using Polaris fluid,then the fluid level could be too high causing it to run up the vent? OPT

Yeah I'm running Mobile1 Full Synthetic transmission fluid instead of the Polaris trans fluid. I was trying to find something good but cheaper than the Polaris fluid, but the Mobile1 is still $10/quart, so maybe I'll just go back to Polaris' $15/quart trans fluid. Or is there another type of fluid that I could run?

If the Side by Sides are like there ATVs they do not use ATF Tanny fluid. The tranny has nothing to do with hydraulics in operation but has chains inside. The 500 Sportsmans for example have a one unit rear diff/ tranny compo and use Chain case oil not tranny fliud.

The Atvs with a separate by itself tranny use chain case oil also and grear oil in the rear diff. All Polaris are CVT operated so transmission fluid is never used.

That's why it's foaming up and coming up the vent. Mobile 1's transmission fluid not a good choice of lubricant for the chain driven gear case or the transfer case either. Best to use Polaris AGL and don't overfill the gear case or transfer case. OPT

I'm not sure about ATV's but the RZR has separate transmission, transfer case, and rear diff fluids. The trans and transfer case calls for the same Polaris AGL fluid that is (if I remember correctly) red in color, so I assumed it was like transmission fluid. Also I read on another forum that Mobile1 full synthetic tranmission fluid is a good choice for replacement, but I guess it's not. I guess I'll just change it and go back to the Polaris fluid.

What causes the fluid to foam up?

AGL is actually blueish/green in color and now even thinner than atf fluid. One of the reasons it doesn't foam up like conventional atf. Yes the gear case and transfer case both take Agl. OPT

Yep, you're right, bluish-green, it's been a while and my memory is horrible lol. I'm gonna change it this weekend back to the AGL and we'll see what happens. Thanks for all the help!