My dealer advised that my 2007 TCH is due for new spark plugs. However, I am not sure why, as I don't think Toyota recommends it...it is at around 140k miles. Also, I also met a man who is a plant manager at a company that makes platinum tipped spark plugs, and he basically told me that as long as they are firing they do not need replaced, as they are made to last the life of the car. Any thoughts from the engineers or maintenance experts out there? Also, I haven't noticed any knocking, misfiring, or reduced mileage. Thanks.

 

BS. You have iridium tipped NGKs in your engine and their lifetime guaranteed is 100 000 miles. You long due new plugs.
Tell your plant manager to learn about metal fatigue and properties change due to high temperature environment they are in.

 

What he said... Replace them ASAP!

I'm getting ready to do mine here next week as well. I'm about 10,000 over due.

Be sure to use compressed air and blow all the sand out from around the coils before you remove them on top of the valve cover and again after you remove the coils and boots and around the base of the plugs.