RE Denso Iridium Long Life (w/ 0.7mm electrode - SK20R11)

Just checked wife's RX w/100k miles and plugs have same .043 gap they had when brand new. Plugs look good and car is running fine.

Several have reported on this forum similar observations with plugs having 125k+ miles. I am asking myself will these plugs ever wear out? Do they ever need to be replaced due to normal wear and tear? Denso will only warranty these plugs for 100k miles although their website mentions the fact that Toyota says they can go 120k miles.

I found a paper that Denso presented to the SAE. It claims this plug was developed to go 200k miles and their research shows they will "easily" do that.

http://www.sparkplugs.com/pdfs/iri.pdf

Interesting reading!

 

Good Morning Art- When I replaced the plugs on my DIL's RX at 97K mi., I bought the plugs before I went to do all the work on it or I never would have bought them. I couldn't believe what they looked like when I removed them, never having had experience with Iridium plugs before. I saved them (don't know what for) because I couldn't bear to throw plugs away that looked that good (and that from someone who has ALWAYS done very conservative maintenance, way before it was needed) I am not surprised at no wear, Iridium is the HARDEST metal known to man, that's why they just don't want to wear out. I am also not surprised at the statement that they would easily go 200k mi. My DIL's also measured the same .043 gap and I know the plugs had never been out.

 

I changed my daughters plugs when we got her 99 at 115K. They looked pretty good, but I figured they couldn't be performing like they did as new. I replaced them (no simple task!!), but I figured why not have a new set for the next 100,000 miles! I'd replace them since you have them. I know they're not inexpensive, but our labor is cheap!

 

That is exactly the philosophy I have. For example, the front struts were not too bad although the mounts were creaking a little. However, I knew they would have to be replaced at least one time so I thought, why not do it now at my convenience and enjoy the improved ride. I may do the same with the sparkplugs and rear coils. If something happens that makes me get rid of the car sooner than planned, eg the trans blows up or we have an accident, I will have wasted some money. OTOH, if I wait 2-3 years to do these "one-time" items, I may not be able to do them myself and that will cost me big time $$$.

 

Hey art,you replaced your struts with kyb`s right?

 

Yes, KYB for the struts but factory mounts and bearings.

 

If I had gone to the trouble of removing the plugs on a RX300 (all of them?), I probably wouldn't put old plugs back in!

But If I'd aready put the back in I wouldn't want to take them out again!

 

Me too!!! I just pulled the front guys. I pulled the backs at 75k or so just to put anti-sieze on them based on a horrible experience my neighbor had with her Sequoia which was only 5-6 years old. Dealer was doing some troubleshooting and discovered a plug was siezed and they broke the head trying to get it out. Led to a major engine overhaul which dealer would NOT accept any responsibility for. What a story. Dealer said plug was melted - no kidding. Ever hear of a melted plug?

No way I wanted to go 13-14 years without pulling/inspecting plugs!

 

Man, now I feel like a donkey... I had mine replaced at 54K and recently 125K at dealer... so basically I threw away two sets of plugs that were probably 1/3 through their life only.

 

I hate to break it to you,but they probably just left the old one`s in their.

 

very true... they figure I'm so lazy *** to DIY, I'm not going to go in and look to make sure it was changed.

I'd like to think that Lexus is more honest than QuikLube and that my additional $95 in parts and labor was put to actual use on my car...

If not, I used up a good $23 in fuel, so there Lexus... blah