I just picked up a 2006 Lexus RX400h. Toyota ATF WS is spec'd for the CVT and the rear diff (the regular RX still uses gear oil in the rear diff - on the 400h, the rear wheels are driven by an electric motor). I found this regarding the fluid. Does anyone know if this stuff is synthetic and is it a decent fluid? The vehicle has 115000 KM on it, the diff takes 2 litres, and when I changed it, it still looked pretty good and smelled OK. Mind you, I don't think the rear diff gets a whole lot of use in this vehicle. It's mostly FWD with the rear only kicking in on acceleration or slippage.