Best Spark plugs

OEM copper, that’s what the manual says for my 2013 4.0 so that’s what I use. Simple as that.

 

That's the way I roll. Simple and what is recommended works every time.

 

Short answer: NGK iridiums
Long answer: For road vehicles, I would upgrade from copper to long life plugs at every opportunity. (Personally I prefer iridium, have heard of too many problems with platinums and the rutheniums are absurdly expensive, so I think iridiums are a perfect balance between cost, reliability and longevity. NGK or Denso.) LL plugs cost more but they last 3x longer, so that is a wash. LL plugs also save time not changing them as often as coppers. My $0.02

 

I've read for the 4.0 engines, its best to stick to the copper denso and all from the dealership. Really cheap as well. Think $4-6 max per plug. 30k mile change interval. So basically every 2 years. Which in my opinion should be a practice anyways. Even if they claim they'll run 50-100k

 

Toyota recommends 120k on the 2.7 plug change. They have looked almost new when I replaced them. Incredible.

 

OE plugs if your not boosted or anything like that

 

I used NGK irridiums or however you spell it. Lol. I’m super happy with them snd my mileage went up though it was running perfectly before I changed them but now even better. Very happy with them to be honest.

 

2nd Gen 4.0L uses the basic copper Denso plugs, roughly $2-3/ea with a 30K mile change interval.

Plug change on the 4.0L is an easy task. I took 1 hour to change 6 plugs on my 1st attempt. I expect my next change will be <45 minutes. At 15,000 miles/year a <1 hour task every 2 years is minor investment of my time. Shoot, over those 2 years, I'll spend more time in oil changes.