Atv Water Crossing.....?

I have a Suzuki ltz250 and was wondering how far i could go under water (or mostly in my case, mud).... I have heard artic cat owners say that if you go above the floorboards, you will find water in your oil... I dont want that, But i have also heard suzuki owners not having a problem with that.... I have rode in water around 5 inches below the fenders (back tires completely submerged).... But it keeps running perfect.... the air intake is under the seat and is covered and the engine is watertight (i think)