Fluid ReservoirThis reservoir is meant for holding hydraulic pump fluid.How to Use:Periodically, check the fluid level in HPUWith the trim tabs completely retracted, the fluid level should be about 2" from the bottom of the reservoir (approximately 22 ounces) refill, remove the Lexan cover and filler plug located at the front left-hand corner of the reservoirFill with any type of automatic transmission fluid (ATF) onlyBrands running HPU with excess or a lack of fluid will not cause damage to the trim tab system