Besides Engine oil, Transmission fluid and Transfer case fluid, there are other fluids that should be periodically replaced.  With time, brake fluid and coolant lose the properties that make them work with their respective systems.  Brakes can feel soft if the brake fluid is not replaced at regular intervals and coolant will not keep the engine at proper operating temperature and or cause a build up inside the radiator or coolant jackets of the engine.  There is also an engine air filter and a cabin air filter that if not replaced regularly can cause performance problems. It is important to the overall performance of your Lexus to maintain all fluids and filters at the proper intervals.