All vehicles except the M5 use automatic transmission fluid (ATF) as the power steering fluid. Use DEXRON®II type ATF.
The M5 has a self leveling suspension that shares a hydraulic fluid reservoir with the power steering system. Use the hydraulic fluid printed on the reservoir. DO NOT use ATF, brake fluid or engine oil.
See Figures 1 and 2
On vehicles other than the M5, stop the engine and remove the dipstick from the power steering reservoir. The dipstick is part of the reservoir cap and is removed by turning the cap. Wipe the dipstick and replace in the reservoir. Remove and check the level. Check that the level is between the marks on the dipstick and add fluid as necessary. Run the engine and recheck the fluid level. With the engine not running, the fluid level may rise above the marks on the dipstick, but this is normal.
On the M5, stop the engine and remove the top of the reservoir. Press and release the brake pedal until the fluid level stops rising. It may take 10 or more pumps. The level of the fluid should be 0.4 in. (10mm) from the top of the reservoir. Add the proper hydraulic fluid as printed on the reservoir. If the vehicle is loaded, do not fill totally to the top. Screw the reservoir top in place.