there is a fill plug located on the front of the supercharger just behind the thermostat housing, you cant miss it. It takes a 3/16 allen wrench. The fluid should be at the bottom of the threads in the fill hole with the engine cold. Use Ford synthetic supercharger fluid, part number E9SZ-19577-A, it comes in a 4 oz bottle, costs about $15 if i recall. my dealer had to order it but only took a couple days. I've been told the GM supercharger fluid will work and it's cheaper, but you dont use very much of it so i just got the ford stuff to be safe....(besides i quit driving GM junk for a reason!!...lol )....anyway it shouldn't use much...when i bought my SC it was way low and i was worried but after i filled it i have only used maybe one tenth of a bottle in 10,000 miles. I just check it when i change oil every 2000 miles or so.....