kalvink

Me too - I am at 70k - checked the front plugs and they look good so I will go until a video or something is up. I was quoted $430 at an indy shop, I can only imagine what the dealership will charge.

idleninjaz

For the 4th Gen RX, the only support fastener is behind the the throttle body, 12mm head very easy to access once you take off the air box.

kalvink

Awesome! Thank you!!

Rgdodson54

FWIW, whenever I do maintenance on my 2016 RX350, I log onto the Lexus site and make an owner entry it shows up on the maintenance performed list along with whatever the dealer has done.

Uzcanadian

yeah it’s criminal how hard to service this vehicle decided to make it.

Rgdodson54

well, I currently have 7 Toyota cars, generally speaking change the synthetic oil as filter every 10,000 miles, the rest of the filters every 30,000, brakes when they are needed and they run fine. Dealers like to sell services that are not in the service manual. I asked the service manager at the local Lexus that I found it interesting that the dealer was trying to sell services that a bunch of very smart folks that designed the car didn’t think appropriate.

350L

​​​​​​Not correct information as far as anyone in the US is concerned.

Spark plugs at 6 years or 60k miles is required by Lexus (Factory/Corporate NOT some dealers) to maintain the emissions warranty in the US. This would come into play on the items within the Federal Emission Control Warranty covered by the 8/80 designation (covered for 8 years or 80k miles). These items are the ECM, catalytic converter, data link connector and MIL.

mikemu30

My 2017 MY maintenance schedule clearly states 120k miles for spark plug replacement.

350L

Mine does too. It is recommended maintenance every 60k. 60k plus 60k is 120k.

Here's a pic from the '17 maintenance schedule:

mikemu30

Nothimg here about plugs at 60k.

350L

I see that. Very strange indeed since on the Lexus website it has it listed for the 2017.

I would call Lexus Corporate to double check if you are worried about maintaining the emissions warranty. I'd say if they denied you, you probably could win in court with your paper maintenance schedule not having that in there, but it'll cost you more in legal fees than the ECM or catalytic converter would have out of pocket!

mikemu30

Odd and if they're iridium plugs, doesn't 60k miles seem like overkill? Any owners out there that already had them changed this soon?

350L

It really depends on the specific iridium plug. Dense has several different lines.. for their power iridium line Denso says they last 60k to 80k but then goes on to recommend changing at 30k​​​​​​.

I think the 4RX is using their long life iridium line which Denso says they last 120k, they make no explicit recommendation to change earlier for the long life line.

In my experience working on cars for 20 years, changing spark plugs sooner than recommended is beneficial. I see increased gas mileage and smoother idle on most standard cars.

On my old turbocharged CRX I changed copper plugs every oil change, but that was more of a race car and saw higher rpms and a richer air fuel ratio than a stock grocery getter.

I'm happy to change the 4RX at 60k and would do so regardless of the emissions warranty personally.

That's just me though, and I like my cars to last for 300k plus. I tend to overmaintain for that reason.

mikemu30

I hear you. I never have and never will keep a car to 150k let alone 300k miles. But I certainly do the right thing maintenance wise regardless. 60k plugs just seems like overkill to me. The last car I actually had plugs changed on was an 01 Grand Prix at roughly 100k and those were probably platinum. Noticed zero difference after the change. Thanks for your input though!

Cocal

Although there may not be a "need" to change the plugs at 60K it's a good idea to loosen them and re-tighten them to ensure that they are not seized n their socket.