Lexus GS300 1998 Owner's Manual page 399

CHASSIS
CHECKING POWER STEERING
FLUID (GS400)
63G003–1
Check the fluid level through the reservoir. If necessary,
R
add automatic transmission fluid DEXRON II or III.
If the vehicle has been driven around 80 km/h (50 mph) for
20 minutes (a little more in frigid temperatures), the fluid is
hot (60_C – 80_C or 140_F – 175_F). You may also check
the level when the fluid is cold (about room temperature,
10_C – 30_C or 50_F – 85_F) if the engine has not been run
for about five hours.
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