It would be found in the warranty & maint. guide., a separate book. Downloadable for free at toyota.com.

 

120,000 miles or 144 months in the Maintenance Guide.

 

Thanks.. Just downloaded it and found it. Page 53 in maintenance log.

 

Just replaced mine. Here's what they looked like at 84K miles....IMO I would not keep them in that long. Even if you take them out, clean them and re-install them its better than leaving them in for 110K miles or more. I just not a fan of the extended use sparkplugs as it's along the lines of extended use/range engine oils on the market today. As you can see from the Y at the end of the plug here, its a factory plug. Oil on the threads since its the plug closest to the oil filler cap. Seepage from lazy techs at dealer doing sloppy oil changes making its way down the plug tube.....

 

This engine runs very lean.

 

Thanks for posting this..

 

My 2010 Toyota Highlander V6 only run 50k miles . It came with ngk double iridium spark plugs. Do I need to replace new plugs,? Thancjw

​

 

It is Denso , not ngk plugs

 

Ir tipped are normally good for 100 000 miles. Unless there's something else going on, like oil leak onto plug, like I had in wife's RX350.

 

I really like this channel on how to maintain Toyotas. He says 120k miles.

As for whether spending more plugs make a difference... The short answer is pick the plugs with the largest gap that comes out of their box.

My one advice is to avoid buying spark plugs from Amazon. There are tons of counterfeits and you won't be able to tell them apart. Buy it from a Toyota dealer or a reputable auto part store. I use RockAuto and they've always been great.