After changing my differential oil in my Wolverine I noticed differential oil blowing out the upper end of the vent tubes that extend up by the air intake tube (just behind the gas tank under the seat.) I did a little research on the subject and I found that this blowby is fairly common on many yamaha atvs. I looked no further than Suzuki for a fix. Part # 27491-38F00 is the fix. I ordered 2 , around 10$ each, and compleatly eliminated the differential vent tubes. The Suzuki part is a bulb that contracts or expands depending on the pressure created by the rotation of the differential gears. This design fully seals your differentials from the elements and is found on many new Suzuki quads (I got the idea after seeing this setup on a 2004 Z250 Quadsport). I did have to buy some vac hose reducers from the local parts store to make the bulb fit to the smaller Yamaha barbs. I will post some pics asap so you can see the finished product. After having this setup for a few months I find that the differental oil seems to look cleaner than before. I probably had a hole somewhere in the factory vent line that I was unaware of. Best of all, no more blowing diff oil!