I own a 99' 4 runner 3.4L w/ 134,ooo miles
and have heard at least 1 tech at Toyota who said the "standard" duel electrode plugs could go for 100K!!!

I think this is wrong as "Toyota" Recomends 30K mile change intervals for standard plugs

I have changed mine twice:
1) changed mine w/ NGK's at 78K Miles after knocking and performance issues
(they looked like Shi*... with large gaps worn conductors, discolored)

2)Change W/ NGK's at 132K miles (plugs did look better but were clearly aged) and i noticed a big increase in power.

What kind/brand of spark plug did you run?

At what mileage have you guys changed your spark plugs?

How did the older plugs look at the specific mileage they were changed at?

When changed, did you notice a power or performance increase?

 

changed mine with factory oem denso plugs pretty sure they had around 50k on them and the wires had 137k on them was running just fine but i changed them anyways they looked fine didint notice any change

 

Denso oem, supposedly the iridium gets a significant increase in hp. I was using bosch platinum till I read a horrid post on how crappy they were. When I pulled them they were seriously toast. I did notice better throttle response and highway pick-up. Stick with the oem that's waht they were designed for. I check mine at every 7k.

 

HEY,
ISNT NGK plugs OEM to???

 

Yes - sometimes the factory used Denso in one bank and NGK in the other. This was my case.

 

Ditto that here, half was NGK and half was denso.

I got OEM from the dealer for mine. An going to put them in this week if it will stop raining!

 

Its 30K its a waste spark system, so it sparks every piston stoke, but only uses every other one for combustion. If you go to a single electrode, its 15K, double plantinum, 60K, double irridium, 100K, single iddidium, 50K... you see the pattern.