I have a 1990 Kawasaki Mule 2010 (KAF540C) with 535 cm3 air cooled single cylinder engine. Need help locating the oil fill location, dipstick location and drain plug location for an oil change. Was told that the engine oil and rear differential share the same fluids. Is this correct? Found the rear end fill plug, sight glass, and drain plug, but the level in the sight glass is several inches below the engine crankcase. How can there be any oil in the engine if the oil level is lower than the engine? Please help! Bruce