It is correct that Lexus state that the gearbox oil is 'for life' and does not require changing, but if you plan to keep the car long term it may be in your best interests to do so. We would suggest having the car serviced by your Lexus dealer if you are maintaining a full Lexus service history but to take it to an independent Lexus or Toyota garage to have the gearbox oil changed. We would suggest that if you car has covered 60,000 miles or more a gearbox oil change would be a sensible decision - you can also ask the garage to confirm the condition of the oil they take out so you can judge when to change it in future.