Bought my '05 Taco used with 80,000 miles on it last year.
Replaced the plugs at 107,000 miles and discovered that they were original
The 3 Denso plugs on the passenger side were all 0.055" and the 3 NGK plugs on the drivers side were all 0.060". All of the plugs were a light tan color with the electrodes visibly worn down but obviously still firing.
What do you bet I'll get better mileage now with my 6 new Densos gapped at 0.039" ?
Guess I should have changed the plugs as soon as I bought the truck. Never assume the previous owner kept up on maintenance. And don't put stuff off. It was quite an easy job to change the plugs with the help from the instructions I got here on this site.