Thanks! A little too technical for me:) but I appreciate your answer!
Tell your (st,d)ealer to take a long stroll on a short boat dock.
There should be no requirement for rear diff'l("AWD") service for the life of the vehicle and the front and center diff'l run in the transaxle's ATF for lubrication
Prior to the adoption of DBW(***), with the advent of the RX330 model, the transaxle was under under extraordinary stress, ATF HEATING, due to a design flaw inadvertently incorporated into the initial RX300 transaxle. Those vehicles, RX300 models, REQUIRE inspection of the ATF condition each and every engine oil change period. My own experience, '01 "AWD" RX300, is that the ATF will begin smelling burned and be darkish in color after each 40,000 miles of ATF use.
I would suggest inspecting the ATF condition under the same above conditions but otherwise the ATF, as stated in my '01 owners manual, should be good for the life of the vehicle.
*** The DBW "fix" for the transaxle design flaw is the causative factor for the 1-2 second re-acceleration downshift delay/hesitation you probably encounter, randomly encounter. DBW is used to delay opening of the throttle plate in response to your gas pedal despression in instances wherein the transaxle has not yet completed the required "re-acceleration" downshift.