petesabine

I purchased a 2011 RX 350 with 107,000 miles from the original owner . The original spark plugs have never been replaced.
My mechanic says the job is very labor intensive to replace the rear 3 spark plugs along with the front 3 plugs which are more accessible. I plan to replace the 3 rear ignition coils at the same time.
Can you recommend inspecting and/or replacing any other items that are more accessible during this repair to avoid additional expensive repair cost in the future?

carguy75

The only thing I would change during the spark plug replacement would be the rear ignition coils that goes on the rear spark plugs, but they generally do not fail so it may or may not be needed. The only issue is that the rear coils will require the same amount of labor to remove in the future as the rear spark plugs if one does fail. I recommend just swapping in new coils now to avoid that issue a couple years from now after the spark plug change.

RX in NC

Be aware that factory Denso or NGK iridium spark plugs will easily do at least 150,000 miles before showing any electrode wear. Some folks have run their iridium plugs for more than 200,000 miles with no degradation in performance. If you are having no ignition-related issues, I would leave the factory plugs in place for now.

Clutchless

I would leave the spark plugs alone until you hit over 130,000 to 150,000 miles. Changing them now will not improve mileage, or running smoothness, or power and is a waste of money. Save up for when something more likely fails.
Do some more important maintenance if it has not been done, such as a coolant change, or brake fluid change or transmission drain and fill.

carguy75

I agree that the plugs may not need to be changed until later, but I am not sure that it is proper to say for a fact that engine will run the same with new plugs as it is now with 100k mile plugs.

However, you got a point that a fluid change(transmission, brake, coolant) would be the better route to go on a high mileage RX.

doji

Have almost 150k on my original plugs. Engine still runs smooth. For now, no plans to change the plugs though I did buy an OEM set of plugs recently just in case I am up for a challenge a summer weekend.

ColAngus

Isn't the PCV valve valve somewhere awkward back there and would make sense to replace during a spark plug swap?
*If the OP decided to swap based on the original post.

Clutchless

The PCV valve is on top of the engine and can be swapped in minutes once the plastic engine cover is removed.

chuyrobles

The plugs are more labor intensive than other cars but it is not rocket science. Just watch some videos and take it step by step. Essentially, you remove the intake plenum and everything attached to it. I have heard but not done the rocker panel removal method. I would leave the coils alone. You can reach in and remove the two of them without removing the plenum. I am about to change the plugs in our 18 RX350 at 60K - it is required to maintain the emissions warranty. After 100K, I can go back to 100K plug changes.

carguy75

The older 3.3 V6 have the PCV valve on the rear valve cover like on my 2007 Toyota Highlander. The 3.5 V6 PCV is easy to get to and change on the front valve cover.

The PCV valve on the rear valve cover near the firewall on the 3.3V6. A real pain to get to on that engine. It is best to change the spark plugs and coils while you are there as well on both engines. I used new rear Denso coil packs on my 3.3 V6 and will do the same on my 3.5V6 when I change the spark plugs.