Interesting thread. Our 2015 RX350 Base has 70k miles and the manual says replace the plugs at 60k. It was at the Lexus dealer for an oil change today and I asked my SA whether we should do the plugs. He said absolutely not, until at least 100k; "it would be throwing away $900." He is a real character from the old school... I was going to have the car detailed and he told me that their detailer is mediocre at best, not at all worth the cost. Very different from when I owned a BMW, and the service advisor was a total crook who advised me to carry out all sorts of unnecessary stuff. Lexus dealerships have a bit of personality; our other car is an ancient LS430 and the SA treats me like I'm King Charles when I bring it in.

 

Well my 2015 RX350 spark plugs had about 192k miles on them before I changed them and the engine was working just fine other than being down on power and fuel economy.

Personally I would not wait that long again to change out spark plugs in this engine, but the OEM spark plugs can go well pass 100k miles before failing it seem.

I would wait until 100k miles to change them if I were you if the engine is running just fine.

 

Our car is at 105k miles and still running good with original plugs, next set will be NGK Ruthenium HX plugs which are upgrade over OEM. Aside from coils you may want to replace valve cover, manifold gaskets and air intake gasket while in there.

 

I replaced the plugs in my wife's 2010 at about 120K miles. Still looked ok. I think between 120K-150K is a good range for plugs replacement.
My 2015 Sienna (same V6 engine) has 130K and I already did the front plugs about a month ago. Will do the rear this summer.

 

Would anyone know why it is NOT recommened to put anti-seize on the spark plug threads? Both Youtube mechanices I follow (Car Care Nut and Viktor G) either stay specifically to NOT apply anti-seize or don't mention and then don't have anything on the threads when installing new spark plugs. Anyone have an explanation?

 

you dont need anti-seize. Grease will change torque, so you might over tighten.

 

Spark plug threads are precoated.

 

With iron blocks the rust was much more of a problem.

Good luck to anyone who can fit a torque wrench ... to me it was an impossible task ... some are easy, some require calculator [if using an offset tool] to and some impossible. I just went with feel.

Salim

 

I easily used an torque wrench on the RX350 front and rear bank of spark plugs. However, I removed the intake manifold which gave me plenty of room to work.