Spark plug Denso or OEM Mazda

The Denso IHKs are my go to for the last 10k on their tune.

Either one, but I found the Denso to be cheaper and easier to get. No issues with them.

You can usually find DENSO IRIDIUM Spark Plugs , which are the OEM Supplier, for about $15 each at any Advance Auto or other major auto parts store.

Yesss got denso coils and spark plugs off their site and they have been great

And, before you get too far, are you replacing with the right plugs? I presume it’s the 2AZ 4-cyl since you’re not asking us how to get to the back plugs. The right ones are the Denso Iridium Long Life or the NGK Laser Iridium.

I use Denso IK20TT and these spark plugs work every time, on both fuels.

I put denso 5310 in mine, apparently they are supposed to give you a slight increase in power if you use premium fuel.

Idk if I gained any power, but the car runs well.

Have used NGK on my Toyota Prius v, works just fine, never had problems.

Changed them recently, still had factory Denso spark plugs, and they worked alright too, even after 121k miles of use.

For what it's worth, I've changed my plugs twice (OEM to Denso to Beru-RS7) and never noticed any oil or any difference in color between the plugs.

I said from the get go that the Densos were running like ****. Especially at wot around 110mp/h it felt like the engine was hesitating and lacking power. Idle was smoother with the Denso though.