To check the front axle gear oil (90w) unscrew the cap on top of the axle on the left side, inbetween the wheel and the engine. The level is supposed to be 1/2 way up the axle you see inside - you'll need to use a flashlight to look down inside. I usually just cover the axle with 90w - easier to see and a little extra won't hurt a thing. If you want to check the trans/hydraulic oil, there is a dipstick on top of the rear axle housing on the left side.