Yeah, so the valve seals are probably hardening a bit and the guides wearing, but this is pretty normal. The white fuzz indicates a little oil build up called ash. Quote, originally posted by NGKsparkplugs.com »DepositsThe accumulation of deposits on the firing end is influenced by oil leakage, fuel quality and the engine's operating duration.Quote, originally posted by [URL »
http://www.gnttype.org/techarea/engine/plugs]As[/URL] shown below, a buildup of combustion deposits stems primarily from the burning of oil and/or fuel additives during normal combustion. These are normally non-conductive. However, when heavier deposits are allowed to accumulate over long mileage periods, they can "mask" the spark, resulting in a plug misfire condition. I was unable to do a copy and paste on this one, but the std Champion spark plug chart (been around for many years. Easily found on the web) states that ash deposits can be caused by fuel additives or more likely oil leaking past the valve seals. This usually doesn't happen when the engine is running or you would see blue smoke from the exhaust (worn piston rings usually cause this scenario,) except in extreme conditions. More often, oil leaks past the valve seals after shut down while still pooled on top of the cyl head, before it is able to drain back into the pan.
FJ's Garage Thread "There is no tool you can buy that will replace experience." - Josh Mills, C.K.DeLuxe January 2011 GenVibe MOTM