Lexus Troubleshooting Questions? Ask a Lexus Expert
Toyota 6-cylinders have come a long way since the 3.0L version back in the day. The 3.5L 6-cylinder is now Timing "Chain" driven rather than timing "belt" driven which makes the more reliable, dependable and durable. It also means less "big job" preventative maintenance. No need to replace the timing chain, as it's designed to last the life of the engine. The Toyota/Lexus 6-cylinder engines these days have minimal "problematic" issues. Basically it's oxygen sensors, bank1 converters and EVAP (emissions control/recovery) System problems with them these days. The RX450 is actually a very tight vehicle. We see very little issues with them (except for the EVAP problems as I mentioned).
If my answer has helped you, please help me by leaving a rating or accepting my answer so I may be credited. Rating or accepting my answer does not cost you extra. It allows me to be credited for my work. Please rate or accept. You can ask follow-up questions after you rate or accept.