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Go with Denso Iridium TT trend or Long Life OE spark plugs?

Posted By: wing0

Go with Denso Iridium TT trend or Long Life OE spark plugs? - 05/04/20 06:16 AM

The manual calls for Denso Iridium Long Life plugs to be changed at 160k km.
Cars at 320k so second swap and I noticed Denso has new TT plugs with smaller 0.4mm center electrode as opposed to 0.7mm in long life.
Previously 0.4mm center electrode is for the "performance" plugs and generally doesn't last as long.

I saw photo from here which is the TT plug after 150k miles or 240k km.
https://www.rav4world.com/threads/a...5-000-miles-pic.82732/page-2#post-926475

I'm debating now if I should just leave the long life in there(first change at 160k didn't show significant wear on the original plugs) or maybe go with the new TT plugs?
Is there any good reason to get long life plugs again over TT?

TT is $4 cheaper than Long Life per plug for some reason even though it's newer. Less iridium = less cost?
Posted By: UG_Passat

Re: Go with Denso Iridium TT trend or Long Life OE spark plugs? - 05/04/20 07:27 AM

I thought the BITOG trend is NGK Ruthenium plugs?

.4 vs .7mm isn't really much material, but at .4mm the laser welding has to be more precise and controlled due to less material to work eith.

The Iridium power doesn't last as long because the ground electrode is standard U-groove electrode, not a platinum tipped electrode.

Iridium TT doesn't have the same gap. It's 0.040", vs the Iridium long life having 0.044" gap, so you would have to slightly open up the gap on the TT.
Posted By: UG_Passat

Re: Go with Denso Iridium TT trend or Long Life OE spark plugs? - 05/04/20 07:59 AM

According to the Denso spark plug manual, https://www.denso.com/global/en/pro...ts-and-accessories/plug/pdf/t-manual.pdf

the longlife has a 0.55mm center tip, with a 0.7mm platinum ground tip, since the longlife plugs start with an "F"
Posted By: adamsoil

Re: Go with Denso Iridium TT trend or Long Life OE spark plugs? - 05/04/20 08:06 AM

Iridium is better for fuel economy
Posted By: bbhero

Re: Go with Denso Iridium TT trend or Long Life OE spark plugs? - 05/04/20 11:08 AM

You don't need to open up the gap.... 0.044 vs 0.040...

In fact that could easily jack up the plug to begin with...

I have the Denso iridium TT plugs in my car instead of the long life Denso because the long life plugs are just too high priced... The Denso iridium TT plugs are also good for 100,000 miles per what they say... So far so good in my car at 65k miles...
Posted By: Dave9

Re: Go with Denso Iridium TT trend or Long Life OE spark plugs? - 05/04/20 05:41 PM

If you have good results with what you are presently using, there is no good reason to change.

I'd swap in the same plugs, not wait, because the older it gets, the more chances of seized plug or fouling. I mean once you have them out to check them, it hardly makes sense to put 160K mi plugs back in unless you have no other choice.
Posted By: BHopkins

Re: Go with Denso Iridium TT trend or Long Life OE spark plugs? - 05/04/20 07:34 PM

How difficult is it to change spark plugs on the car? If it is relatively easy, then give the TT plugs a try. If you don't like the way the car runs with the TT plugs, then change back to a set of Long Life.

but if it's a bugger to change plugs on your car, then stay with the Long LIfe. You have proven history that the Long LIfe have performed to your expectations.

That said, I've always been one to stay with the original plugs that were spec'd for the car. With the exception of a VW Dasher that ran better with a set of hotter plugs, but same brand as original, I've always found my cars to perform better by replacing plugs with the same brand and type that the car was spec'd for.
Posted By: Amkeer

Re: Go with Denso Iridium TT trend or Long Life OE spark plugs? - 05/06/20 10:21 AM

Use the Iridium plugs and change around 80,000-100,000 miles.
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