Differential Fluid
WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2002 Lexus SC 430, 2002 Lexus RX 300, 2002 Lexus LX 470, 2002 Lexus LS 430, and 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
Under normal driving conditions, inspect differential fluid every 15,000 miles or 12 months, whichever comes first. Under severe driving conditions, replace fluid every 15,000 miles or 12 months.