How many miles?

 

These spark plugs were used for 13 years without changing for 145,000km in 1UZ-FE engine for

Celsior UCF21. The other 4 plugs are not pictued but they look exactly the same.

Using a gauge, I measured the gaps and the results were all 1.12mm.

They are still holding the capability to work well. It didn't show any problem before changing them but

already almost 50 % additional distance was run and it was a bit late to change.

After changing all 8 spark plugs, I did not feel any significant difference. The only thing I can say is that

the engine starts a bit quicker after heavy rainy days.