NGK plugs wear faster than Denso?

So after 4 years & 33k I finally changed the plugs in my 2012. I pulled out the passenger side Denso plugs and the three put in at the factory measured out at .046. Not bad considering .043 is spec. Strangely the driver side three NGKs from the factory measured out at .050. Is this typical in your experience with the two brands in comparison? I asked the local Toyota why they put two different brands in the V6 and they said it was a contract thing. Did someone at the factory gap the Densos a little tighter than the NGKs or do the Densos just last a little longer? Can I put iridiums in a 2012 or should I stick with these standard $4 plugs?

 

I'm changing plugs tonight after 8 years and 191k miles on the factory plugs. Still runs and drives good just gets poor mileage. I'm curious to see what they look like. I'm putting Autolite Iridiums in it. Did a little research here and many say to just use the cheaper NKG's instead of irridiums. I already had the iridiums bought so I'll stick with those.

 

Are your factory plugs iridium? I think the dealer said 120k mile changes on the iridiums, but they wanted $20 each. I thought $120 was a bit too much. Oreileys gave me a military discount so the standard Densos were under $4 each.

 

According to what I read here, the factory plugs will be NKG's on one side and Denso on the other side. Neither are iridium from what I understand.

 

That's true but doesn't the 4 cyl. use the iridiums?

 

Yes, all the 2.7 liter Tacoma's use iridium tipped plugs from the factory.

 

153K on my factory plugs, never a dip in MPG. I guess I'll change them someday, but it's really hot out this month here in Central Florida.
Need to wax the truck too, same excuse.

 

4.0 trucks use copper and the plug change interval is 30K miles. I did mine at 45K. The NGKs had a slightly larger gap. I replaced with irridium and will eventually get around to them around 100K. 75K now.

 

I noticed that my NGKs showed more wear than my stock Densos as well

 

This seems to be the case is most instances.

I replaced with Denso copper plugs per the manual.

There are many threads where folks go back & forth on "what's the best plug" argument.