Spark plug gaps grow?

[Sonic dB]

I changed the plugs last night....after 25,000 miles driven in the past 9 months or so. I wanted to do it sooner, but have been very busy.

Most of them were slightly crusted white, which would indicate a lean running condition...but they werent bad.

What got me was that upon measuring the gaps on the ones that I pulled, most of them were FAR above the factory specified .028mm....which is what I gapped them at when I put them in last year.

Measurements ranged from .035 to .045...How is this so? Is that much of the plug worn away over time and miles...or do they just loosen up?

Can ran great with the old plugs...running slightly smoother today with new ones.

[Zeke]

The electrode wears shorter.

[Por_sha911]

Is it possible that you are running too lean and its affecting the plug?

[Sonic dB]

I dont know. The O2 sensor is pretty new, like 9 months old.... Car runs like a champ. I use 91 or 92 when its available and shoot it with Techron every month or so....maybe too much Techron?

On the positive side, there were no signs of oil buildup or heavy carbon.

Milts probably right...I just never noticed this electrode wear issue before on any other car that I owned.

Plugs are Bosch WD7 copper

[rich22]

IMO that's pretty good life for non-platinum plugs. I change at the recommended 50k interval for platinums and the electrodes are burned away quite a bit. In the bad old days of the 70's and 80's, I used to change plugs at 12,000 miles and the gaps were burned away to almost double the original gap. Some recommended services were to pull and re-gap plugs at 6,000 miles.