litespeed5

Hello Club Lexus!

I just purchased a used 2010 Lexus RX350 with 127k miles.
The manual suggests to replace the spark plugs at 120K miles. I noticed only 3 of the spark plugs are easily accessible. I did a forum search to find more info, and it looks like replacing the other 3 will be a big task (same process as the 2RX).

According to the Carfax, the car had 90K Service done at a Lexus dealer in California. That was the last service recorded on the Carfax.

I removed one spark plug to inspect it. It looks different than spark plugs I've changed in the past (I'm used to working on older 90s cars). The tip of this plug is very fine.

Does this spark plug need to be replaced? Does this look like the original spark plug that came with the car?

It is possible that the spark plugs were changed during the 90K service. I guess what I'm asking is, Does this plug look like it is 127K miles old? or 37K miles old?

Thanks for any info you all can provide.

carguy75

The RX350 should have the Denso Iridium long life spark plugs(FK20HR11).

The spark plug in the picture you posted looks like it should still be good by the color and condition of the electrode which do not look too worn or blacken due to excessive carbon.

However, the rear bank plugs could be a different story.

I would change the plugs out to be sure since you have to dismantle the top of the engine and cowl to check the rear plugs anyway.

I changed the spark plugs out on a Nissan Murano and it is the same process as the RX350 from what I researched in the Lexus service manual.

Here is the post I posted in the Murano forum that shows how involved the RX spark plug change could be.

http://www.nissanmurano.org/forums/8...ug-change.html

You will have to removed the cowl/wiper assembly, the intake manifold/throttle-body to access the rear bank plugs.

If it is as tedious as the Nissan Murano spark-plug change then it would be a 2 hour job at the minimum.

FYI, Iridium firing tips are very small, usually .07mm on OEM plugs.

Denso makes Iridium Power plug that has .04mm firing tip in which I used in most of my old cars.

However the Power plugs only last about 30k miles so that plug would not be good in the RX350 considering how much work it is to change the plugs.

I made the mistake of putting the Power plugs in the Murano at first and swapped them out latter for the long life plugs.

The plugs you used in the nineties mostly likely had nickel or platinum firing tips which were larger from 1mm(Nickel) and .09mm(Platinum).

The smaller the tip the hotter the spark which means more power/efficiency from the combustion process, hence why Iridium plugs are being used in many modern engines.

Clutchless

You need to go to the Lexus owners site linked below. Join it and enter your VIN. Then you can see the dealer service history for your vehicle and determine if the plugs were replaced. If it is not entered as some dealer are slow to update, you can always call the servicing dealer and ask! https://secure.drivers.lexus.com/lex...-lexus/home.do

If you work on your own car, the www.toyotanation.com site forum for the Highlander (the mechanical twin of the RX) has lots of how to posts on maintenance items, such as the ordeal to replace the rear plugs.

litespeed5

Thank you guys for the responses! The links are very helpful!

carguy75

You are welcome.

I always try to help a fellow DIY'er if I can.

FYI, I typed the incorrect firing tip sizes.

I should have typed .4mm,.7mm, and .9mm instead of .04mm,.07mm,.09mm.