40,000 Mile Spark Plug replacement on 2016 CX-9

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2016 Mazda CX-9 GT
Greetings All,

I have been cruising on the forum for some time now and have my first question. I was reading in the manual for my 2016 CX-9 and noticed it says to replace spark plugs at 40,000. Sounds a little premature right? My other car states 100,000 miles. Also the spark plugs are like $22 https://parts.coxmazda.com/p/Mazda_2016_CX-9-Signature-FWD/Spark-Plug/66672756/PY8V18110.html

Does anyone really think this is necessary to be completed at 40,000?

if the owners manual says 40k miles, I would at least take them out and check to see if they are worn or not.
 
Do we know if they are a commonly available plug we can buy almost anywhere, or if they are a special plug made by Denso or NGK for Mazda that we can only buy from a dealer?
 
Do we know if they are a commonly available plug we can buy almost anywhere, or if they are a special plug made by Denso or NGK for Mazda that we can only buy from a dealer?

You should be able to buy them anywhere. I recommend NGK or Bosch
 
Greetings All,

I have been cruising on the forum for some time now and have my first question. I was reading in the manual for my 2016 CX-9 and noticed it says to replace spark plugs at 40,000. Sounds a little premature right? My other car states 100,000 miles. Also the spark plugs are like $22 https://parts.coxmazda.com/p/Mazda_2016_CX-9-Signature-FWD/Spark-Plug/66672756/PY8V18110.html

Does anyone really think this is necessary to be completed at 40,000?


I plan to replace as needed all top side components of the ignition system, fuel delivery system and EVAP system once every few years. The type of driving done over that time period and the results of various diagnostic test results on those same components will determine what (if anything) gets repaired or replaced. If the test results come back good, but I notice visual wear and tear on certain parts, then I'll start replacing things. Should be able to do all of this without taking it to the dealer.
 
2016 cx 9 - has 70K miles - dealer suggested spark plugs change- any instructions floating around for the newer (post 2016) cx-9 how to get to the plugs and any special instructions... anything else to replace together? thanks.
 
There is a video on youtube which shows a spark plug replacement on a second gen cx-9. Watch it and see if that helps. I have a first gen so I really can't say if the video is useful or not. I was looking for a video of a first gen when I stumbled on to the second gen video.
 
Thank you. I watched it...seems straight forward. Anyone here have recommendations which plugs ? should I stick to Mazda oem? 2016 cx 9 touring.
 
At this moment you have no choice but to go with OEM. Get them at an online Mazda parts dealer like medcenter mazda to save a few $. The Mazda spark plug for the 2.5l turbo is definitely a NGK product DILKAR7M8 - but not available anywhere except at the Mazda dealer under the Mazda part number PY8V-18-110
 
Thanks for posting morenar. Adding a link to this in the CX-9 Resources.
 
No problem. He has other videos for things like brake replacements on the CX-9 as well as other maintenance items.
 
Just had this done at my dealer - ended up being over $200! Car feels like it has more power but my gas mileage has dropped a bit since. Could just all be mental on my part.
 
The car is peppier with new plugs. No reason for the gas mileage to drop unless you're having more fun and stomping on the gas pedal more. (Or the mechanic left some hose or wire disconnected.) You'll need assorted 8mm & 10 mm sockets & end wrenches to loosen the relay tray for access to the plugs. The spark plug socket is a 14 millimeter, not one of the common spark plug socket sizes.
 
U.S. NGK web site now shows the plugs we need. O'Reilly has about the same price as an on-line dealer. That's good to know, and they even show them in stock in my local store.
 
From that video that guy puts a ton of anti-seize on the threads. Put as little as possible. NGK recommends to NOT use anti-seize on the threads because the threads are specially plated to prevent seizing. However, if you DO use anti-seize, be sure to reduce the torque applied (they recommend by 20%) because the anti-seize reduces the amount of thread friction but not the thread tension. Torque wrenches aren't affected by tension, so you could damage your head if you're not careful.


Also, I didn't notice him using any dielectric grease on the plug boot. The purpose of that is to seal it in and prevent moisture. Be sure to use that, it's cheap and a really good idea.
 
So I finally got around to changing the spark plugs. Since I bought the car back in January with around 99,000km, I wasn't sure if the previous owner changed them out at the 80,000km mark as they're supposed to. It turns out they didn't. So good thing I changed them now. Here's what a plug with 101,000km looks like. Not too bad but some very distinct singe marks on the base of the boot. The electrodes seem good, even checked the gap and they're still in spec. 👍🏼

PXL_20210302_234008202.jpg
 
So I finally got around to changing the spark plugs. Since I bought the car back in January with around 99,000km, I wasn't sure if the previous owner changed them out at the 80,000km mark as they're supposed to. It turns out they didn't. So good thing I changed them now. Here's what a plug with 101,000km looks like. Not too bad but some very distinct singe marks on the base of the boot. The electrodes seem good, even checked the gap and they're still in spec. 👍🏼

View attachment 296048

Nice, how was the job? Fairly easy/straightforward? My CX-9 just hit 53k so I've got little more time before I change mine out.

Where did you order the plugs?
 
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