Anyone have any ideas why this happens? My friend is also finding gas in his oil. The quad has pretty low hours on, it but he has done zero maintenance on it over the years, besides changing the oil and cleaning the air filter.

dont know about gas in the oil but coolant could be leaking into it from a worn gasket, which will eventually cause it to over heat and blow up. I had it happen to me, when i had a yamaha.

my guess is that if he has taken little or no care of it that the rings are shot and passing not only some raw fuelpast the rings into the oil but its also presurizing the cases with blow bye and squirting out the breather...

just my guess....hopefully it is tuned right....and hopefully he starts to take care of it a little better...

I agree on the rings assesment. I bought a raptor with a bad top end that did the exact same thing. He needs to fix it now before one of the rings breaks, or piston slap breaks his piston skirt off and destroys his crank and maybe his cases.