O.K. Guys and Gals. Just hit 57K on my "98 GS4. Thought I would do the 60k service early and put in the TM spark plugs. My question is how long before I should replace them again? How long do they last?
Will

 

i remember reading that they last for a long long time, like 100k?

i have had mine for 10k miles, running strong

 

Henry,
Some people claim they notice a smoother idle, better engine response and fuel economy with TM plugs. Did you notice anything?
Will

 

Why not stick with the OEM plugs? I remember a few years ago when SPLIT-FIRE everyone thought they were the best thing since Swiss cheese but now were are they? They designed the motor for that plug then why not stick with it? Just wanted to hear what you would say on this?

 

Well... they designed the GS you're driving with different wheels, different alarm system, different exhaust, etc, right ? Same answer. Do a bit of searching on the dyno Mean Gene did on the plugs for a good reason why.

Will, I think they are long life plugs, but I personally don't believe any plug will give you 100% duty for over 25 - 30K miles. I'd change them after 30K for a fresh set. My GS only has about 70K and I've had five sets of plugs in it. Butt-dyno (or mental dyno) tells a difference in the way the car runs every time I put a fresh set in.

 

Lex._Kid,
I've heard so many good things about these spark plugs, I thought I would try it out for myself. Personally, I don't notice anything out of the ordinary. I did have to remove my SRT intake, so I can smog it. I'll see how it feels after I put my intake back on.

Dave,
The Iridium spark plugs in our cars should last a long time. Lexus/Toyota recommends replacing them at 90k miles. Just curious if you put iridium back in everytime you replaced them.(those spark plugs aren't cheap)I have elected to replace them now, at 57K miles. Which brings me back to my original question of when should I worry about replacing them again?

Will

 

Yeah, I'm aware of the 90K service interval. I'm fairly certain they will last that long, but I'm also fairly certain they will lose a good bit of their performance by that time.

I used Irridium plugs the first time I changed them prob at 35K, TM plugs the second at 45K, Irridium plugs the third at 65K (because I couldn't get a set of TMs in time). I ordered a set of TM plugs to install because I could tell a difference in power (and dynod lower) without the TM plugs, but ended up getting my supercharger installed at 68k... which uses denso lower heat range plugs. Fouled those and put a clean set in for number five.

As I mentioned above, I'd personally change them after 25 - 30K. But I'm **** about getting max performance out of the car that I can.

 

hard to say. i did mine at 50k, so any new plugs would have been better than the old ones. the car did get smoother or so. i think we did dyno but not conclusive reports on the power or so. to me it's just routine work. would i do it again? i am not sure. if their price is ok why not. otherwise i don't see much issue with the stock ones

 

I've had mine for about 25k miles. Everything seems to be running OK. I have not looked at the plugs though.

 

Dave,
It sure doesn't hurt to take the steps you've taken on the spark plugs. I think what I'll do is take them out after 30k. Then I'll decide if I want to replace them or put them back in. It does seem to idle smoother, but when I did the 60k svc, I also cleaned out the throttle body, which was gummed up a bit, so I'm not 100% sure if the TM plugs were what cause the car to idle smoother. Thanks for all the input Guys.
Will

 

How much were they and were did you order them...?

 

Carson can get them...I think they are around $10/ea.

 

they did great in the performance department for me!!! here's my dyno on my last car! haven't been able to get them into the new one yet......money got tight after the tranny rebuild!

https://www.clublexus.com/forums/sho...d.php?t=312097

 

They have been very good plugs for me, especially as far burning the cruddy gas I have in Mexico. Goes very well with intake modifications.

 

love the TM plugs......

seem to last forever as I put them in 40K miles ago.....but after reading Dave's comments, looks like the time for another set.