What is the current best spark plug for the 2.5 engine? My 2016 CX-5 Tour is closing in on 70K and when I do the next oil service, I plan to replace the front wheel bearings (starting to make noise and getting worse) and also plan to replace the spark plugs a little early. Yes, I know 70,000 is a little early but some of the roads I drive you know are roads because they don't have large trees growing on them.

 

NGK iridium is the way to go,


My 2¢

 

And here I thought wheel bearings were a Subaru issue- I guess not...

 

wait , what you have 70k miles on a set of spark plugs? if that so spark plug should wake up your engine's performance and MPG.... lol


I personally use a ordinary Champion copper old school plugs in my 2018 Skyactiv Mazda 2.5 engine for both spirited engine running and daily driving (NGK only when they are on a great sale price point) and I suppose for the long haul of commuting or vacation driving just use what MAZDA had in your engine when you purchased it new. But next time don't wait more then 30k miles at the most before changing them. That is unless you like the slow progressive loss in engine performance.

 

IFAIK most all current production vehicles (gas engines) come with platinum spark plugs. Iridium plugs are a step up.
Most all of us here, install and forget. So long life is the primary consideration. Iridium gets you that.
Supposedly good for the full 100K the factory plugs are supposed to be good for.

My 2¢

 

I read your personal recommendation on NGK "way to go" response but said nothing. LOL
Sometimes I wish you would post and then leave it at that.
But because I posted you just couldn't leave it alone LOL


So you buy into that they will last up to 100k miles. Hmm how many have perfect condition on their engine? Almost no one. The best spark plug currently manufactured and offered to the general retail customer will not perform well and start degrading after 30k miles or sooner depending on engine health factors to name a big one.. Just because that spark plug will fire does not mean it is producing the best kernel which effect things like engine output and MPG. It gets old and funny when you think about how poorly the engine must be running but ignored or not even noticed by the owner and that same person bragging how long they go before changing spark plugs and the engine runs just fine. LOL

To answer questions about what spark plug to use on forums always a debate. Much like asking what tires are the best. But unless there are members that are into the hobby of spark plug testing and evaluating with proper measuring equipment most simply read the latest HYP on advertising or what the majority seem to feel is the best and go with that . Than after using a choice spark plug will report wondrous examples of the level of performance and longevity they get with their chosen spark plug! I have literally chapters full of testing spark plugs using a DYNO and a good old fashion oscilloscope, EGT, EGA and a few other monitoring equipment for testing and evaluating spark plugs that debunks 95% of the BS about spark plugs posted on forums and even from a few spark plug marketing advertisements. I am even a technical contributor with articles on the topic of spark plug over the years in a few car magazines . Some of my information is on ,how to gap and install and even choose a totally different spark plug type in any given engine outside the recommendations of the OEM. When the often times I try to post a little info and insight on forums about spark plugs I get the DIYs and even some professional service "mechanics" that will argue what I "claim" even when I point out how they can find for themselves what's really all about spark plug performance and longevity just from performing some real world testing.



There is actually much more, and the write up continues into detail information, but you get the point, or like always NOT!

 

The repair manual says to change them out at 75,000 miles. I remember changing points, condenser and plugs twice a year. I'm changing a little early just to stay up on maintenance. As for performance and fuel economy, I have noticed no change since I bought it as a CPO with 19,500 on it. I'm surprised I haven't gotten a ticket in this little red pocket rocket. I still get 27-32 mpg on the highway. The only complaint I have about the car is sometimes I run out of room. Beyond that, I like the car. Except for some scratches from road debris in Hurricane Ida last year, it looks new.

 

Well then maybe you should just follow the repair manual.
Why did you start a thread to ask about a spark plug recommendation?

 

I wasn't intending to bruise your tender ego, I was pointing out that for the majority of us here, we just want good running
low maintenance vehicles. Most American made, or branded American, vehicles suggest spark plugs last about 100K.
Now boy racer types obviously will be more concerned with tip top performance, changing plugs, oil, etc. on a much shorter
schedule. Few here are likely to keep our Mazdas past 200K, not that they couldn't do that. I've heard of a Mazda 6 that ran well
but made it to 600K with little repair costs. High ends plugs will work fine for most of us for the 75K or more.
YMMV.

​​​​​​​My 2¢

 

Because my repair manual was printed 6 or 7 years ago. When I ran a shop back in the early 1980's, I got a lot of work because of assumed knowledge. It's always possible that several years of practical use has shown something to be better in real world use.

I caught a lot of flak on another forum when I told someone to NOT put a cooler thermostat in their truck as their mileage would tank. You wouldn't believe the responses. A cooler thermostat creates a denser charge. Well, it did back in the early 1980's and back. With fuel injection, there is no choke. The computer goes into "open loop" mode to warm the engine up. It gets stuck there with a cool unit and wastes fuel and eventually can melt the catalysts in your converter.

I've also modified my CX-5 to handle rotational inertia better than factory.