Fouling resistant spark plug

[0016]Insulative sleeves available from Autolite were coated with a 22 weight percent dispersion of one of three glaze coatings in acetone. Weight percent is based on the total weight of the dispersion. The glaze coatings are shown in Table 1. VIOX 17930 comprises a silicate glass comprising Al, B, Mg, Ca, and Sr as modifiers and is commercially available from Viox. Mod-3 comprises a borosilicate glass comprising Ba, Sr, Mg, Ca, and Na as modifiers and is commercially available from Viox. The glaze coating was applied as a band starting approximately 1 mm from the top edge of the insulative sleeve and continuing to the gasket seal location on insulator. The insulative sleeves were then air dried for 1 hour and then heated to 850 degrees Celsius and held at that temperature for 1 hour. The insulative sleeve was then combined with the remaining elements to form a spark plug. The spark plugs were tested in an accelerated road test. The spark plugs were put into service in a van using gaso