I recently changed my plugs, using ND PK16PR11, and noticed that all of the used plugs have a white coating on the ground and center electrodes; under a magnifying glass it seems to have a rough texture, almost like calcium build-up on some water pipes. The seal has a black coating on it. All six plugs look the same and have been in for about 1 year. I changed them because I've been getting the blinking CEL more frequently lately, other than that (and the oil consumption) the vehicle runs great. Does anyone know whether this is normal; if it isn't, what is causing it and how can it be corrected?

These plugs cost almost $7.00 each; being of Scottish decent:2cents: , I thought about trying to clean these up well enough to re-use:iceslolan . Any thoughts on this strategy?

Thanks much for all your feedback!:icon16: