Spark plug comparsion

my opinion is that there are too many counterfeit plus out there to risk not buying from a dealer.

 

No one can reliably tell you that. I’ve tried the first three on the list because I changed mine multiple times (after getting counterfeits, after clogged intake, and after head gasket job). There’s no perceivable difference between any of em.

 

My take would be that the spark plug's job is to ignite the fuel-air mixture, consistently, under all of your driving conditions.

If plug A and plug B both do that, neither one is better. If plug A does that and plug B doesn't, A is better.

With a scan tool, you can watch an ECM statistic called "misfire margin" while you are driving—ideally in a range of conditions (datalogging helps). The margin is kind of a sliding scale. Negative numbers are bad news ("in the negative zone, a misfire is occurring"). Positive but under +30 is still "a high likelihood that a misfire is occurring." The farther above +30, the less likely.

If you've got low misfire margins with plugs you've got now, and new plugs push the margin up into the "well above +30" range, then the new ones are doing the job. IMO, once the job is getting done, a fancier plug is pretty much vanity.

If you try one style of new plug and see low misfire margins, say dipping below +30, and then you try another style and the margin is better, then stick with that style.

I think I'd start with the Toyota-specified plug and, if I saw a nice high margin, just keep it and call it a day. I'd look for something else only if the margin showed a problem with the plugs.

Some of the 'enthusiast' plugs are made with very skinny electrodes. Those do fire more easily, which is a benefit if you have evidence that the ones you've got aren't firing easily enough.

Otherwise, the skinny electrodes just mean shorter life, and the Toyota OEM tradeoff of a slightly fatter electrode that still reliably does the job and lasts 100+ thousand miles makes sense.