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Question change spark plug on 2009 mazda6 3.7L V6

So I was about to change spark plug on my 2009 mazda6 V6, I bought six of these spark plug according to NGK website:

NGK ILTR6B11 Laser Iridium Spark Plug

NGK site says these are preset to 0.044, 2009 mazda manual says for the V6, GAP should be 0.051 - 0.057

so I have three options:

  1. regap the NGK to 0.54 and put them in, from what I read the tips on these plugs are very easily damaged…

  2. leave them at the current gap and install them at 0.044, would that cause any problem since mazda calls for a different gap size??

  3. don’t change the plug at all, my car has 123k miles, but no misfire or noticable mpg drop, one guy told me they can go to 150k or 200k miles no problem.

The shop will charge me $180 to install them, plus the plug I paid $60 that’s $240… I miss the days I can just change the plug myself.

what should I do???

Looks like those will work but please read these:

Are those NGK plugs identical to what the Mazda came with from the factory? No real benefit to change, and different plugs can cause problems in some cases. I would use the exact brand and model plug that is coming out.

I always go with the vehicle manufacturers recommendation. They know the engine a lot better than the spark plug manufacturer. I would go with @texases recommendation here. You’ll probably save money as well.

I think I’d make sure I had the identical plugs. All I’ve read about iridium is that it is too brittle to regap. The last thing you want is for the electrode to break off in the engine, but I’ll defer to what the pros say.

The engine on my 4runner calls for Standard Copper plugs. NGK makes the standard copper plug (they are an OEM provider for Toyota)…they also make a Platinum plug and a Iridium plug for the same engine. Some people believe the hype about how much better performance the Iridium or platinum plug…when in truth…there is no performance gain. In fact Copper is a much better conductor that it usually has a slight edge in performance. On a 4runner web-site some of the contributors there swear up and down that they’ve seen HUGE performance gains in Iridium plugs. Which is funny since Iridium plugs were just designed for longevity…NOT performance.

so I’m thinking I should just leave the plugs in there? I called one mazda dealer, they want $420 just to change the plugs including parts and labor what a rip off

the shop says i should leave it at 0.044 but I’m really not sure since the manual says otherwise.

So I’m just going to leave the plug in there…

I belive these are OEM mazda6 plugs. the NGK laser iridium

Here’s a guy who did it with the NGK plugs gapped at .044:

For $420, I’d do it myself and leave the NGK plugs pregapped ot .044.

so I'm thinking I should just leave the plugs in there?

No - Replace them. Just replace them with the OEM recommended plug.

Iridium plugs may be the correct plug. They are for my wifes Lexus. The main reason is that those back plugs are a royal pain in the butt to replace. NGK only makes Iridium plugs for that engine.

The point many of us were trying to make…is you probably don’t need the extra expense of Iridium plugs (usually 4-5 times the cost). If the plugs are difficult to replace then they might be worth the cost.

@Mike, well, he’s already bought the NGK Iridium plugs.

@ michaelscai

The mazda manual shows this:

I couldn’t cross reference the number given (CY01 18 110) with anything from NGK, Denso, Bosch, or even Autolite. All those say they have a plug that will work. But as others say maybe just stick with what Mazda recommends. I know my Toyota runs best with what is listed in the manual.

yes I bought the NGK laser iridium because the plugs are a pain in the butt to change on this car…

also since the manual says 0.051 - 0.057, i don’t feel comfortable putting in the pregaped ngk in there.

I think NGK is the OEM plug, but I can’t confirm this.

Only the cathode is iridium, the anode (the part you bend) is steel and may have a platinum disc on it. If you have a spark plug adjusting tool with wire gauges, you can bend the anode by using the appropriate slot and bend gently. The trick is in checking the gap. Do not apply very much force on the wire that you are checking with, that is where you may damage the tip.

You put the slot near the bend in the anode, away from the cathode (tip) and the disc (if equipped).

what happens if I don’t do anything? car still runs fine, maybe not as fast as new but hard to tell…

ok i decide to do nothing …dont want to spend 300 to do it… car runs smooth right now, maybe i will do it when it hits 150k miles or 200k or when it start missfiring

The problem with waiting forever to change the plugs (other than the obvious misfiring which may create other problems) is that sometimes plugs left in for that long may not want to come out without destroying the threads in the spark plug holes.

Those plugs can be regapped but care has to be used when doing it. Do NOT exert any pressure on the center electrode at all.

“ok i decide to do nothing …dont want to spend 300 to do it… car runs smooth right now, maybe i will do it when it hits 150k miles or 200k or when it start missfiring”

Yeah, I’ll just wait to go to the dentist until my teeth hurt or gums start bleeding. I don’t want to spend money on maintenance, just repairs.

OK seriously, you’re already overdue for spark plug service. The fact that the car seems to run fine doesn’t mean that it is. There may be more hydrocarbons coming out of the engine that the catalytic converter has to clean up. The firing voltage across the spark plugs is probably higher than normal, causing excessive load on the ignition coils. Fuel economy may be less than it used to be. Why do nothing? It’s simple routine maintenance that all cars need.

well I really wanted to do it, but the dealer wants too much, the shop has no clue if the gap needs to be reset… so all things considered, it might cause more problem than not to replace it.

is it too late to replace it when engine misfires?

the mpg hasn’t gone down much if at all since 70k miles, and it idles smooth.

I looked up iridium plugs on line and all are per gapped to 0.044 inches. It appears that if you use the NGK plugs you bought, 0.044 is the correct gap. Rock Auto says not to change the gap for most of the plugs they offer of this type for your car. Put the new plugs in and drive it.

The plugs listed for the car probably also fit in other engines. The .044 gap is most likely set to work for all these engines even though each engine has it’s own recommended gap that is not .044, like the OP’s. But, it will not provide optimum spark if it is that far out of gap. You may have issues down the road with fuel mileage and starting issues.

I put iridiums in my car last year. The trick to gapping them is to bend just the anode with a tool that doesn’t touch the cathode. The cathode tip is very hard, but also brittle. Any shear force on it can break it. Being that this is most likely the last set of plugs for my car, I wanted to use the proper gap that the manufacturer recommends. I used one of these, and did not touch the cathode.