Spark plug Denso or OEM Subaru

I waited till like 100k to do my spark plugs on my 2013 Crosstrek, they were still good just not as efficient

Just traded in my 2015 Forester with 219,000 miles and the original spark plugs.

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.

Normally that's a result of a failed spark plug seal. If you have no other problems I would put new spark plugs in it and check them at the next oil change.

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 have the 24's, not impressed.

the densos work fine, the point of swapping is not for any performance gain, rather to prevent shattered ceramic from raining into your cylinders