Having worked with dozens of these powertrains, I can tell you the 2023 RX 350h engine is remarkably low-maintenance compared to conventional alternatives. The oil change interval is officially 10,000 miles, but I typically recommend 7,500 for customers who do a lot of short trips or extreme climate driving. Use nothing less than full synthetic 0W-20—I prefer Toyota/Lexus genuine or Mobil 1, as they've consistently shown excellent protection in used oil analysis tests I've run. One overlooked maintenance item is the engine air filter; the hybrid system often runs at lower RPMs, which counter-intuitively can lead to more dust accumulation over time. Check it every 15,000 miles rather than the manual's suggested 30,000. The coolant system is a bit more complex than conventional vehicles, with separate reservoirs for the engine and inverter circuits. The inverter coolant (pink) typically needs changing at 100,000 miles, while the engine coolant (also pink in the 2023 models) follows a 120,000-mile schedule. Don't mix them up—they look identical but serve different purposes with slightly different formulations.

One quirk I've noticed in the shop: the 12V battery in these hybrids tends to fail more abruptly than in conventional vehicles. This happens because it's not constantly charged by an alternator but rather periodically topped up by the hybrid system. When replacing, stick with an AGM battery—I've had good luck with the Lexus OEM or Optima Yellow Top as alternatives. The transmission fluid is another point of contention. Lexus claims it's lifetime, but I've seen noticeable improvement in shift quality when changing it around 60,000 miles. It requires Toyota WS fluid specifically—using the wrong spec can cause serious damage to the valve body. Finally, the brake system deserves special attention. The regenerative braking means the physical brakes are used less frequently, which can actually lead to premature caliper sticking. I recommend a thorough brake inspection annually, even if the pads show minimal wear. Have your technician exercise the calipers and lubricate the slide pins to prevent premature replacement needs down the road.