[TGPilot]

Are the deposits crusty white or smooth white?

Crusty chunky looking deposits are normally from fuel additives.

If the electrode is covered in a real smooth (not glossy) white residue then most likely you are getting coolant in your cumbustion chamber. It is hard to get coolant in all cylinders though. Maybe a tan colored or off white is what you are seeing. If it is off white towards tan you are running lean.

Also look up in the base of the plug. If you are darker colored up there and light colored down on the electrode then you are running rich at heavy load and clean to lean during cruise.

There is a science to reading plugs and I am not an expert by any means. You may want to do a google search on plug reading to properly read your plugs. Just a suggestion.