A common use of this type is in the high-voltage connection associated with gasoline-engine spark plugs, where grease is applied to the rubber boot of the plug wire to help it slide onto the ceramic insulator of the plug, to seal the rubber boot, and to prevent the rubber's adhesion to the ceramic. Such greases are formulated to withstand the high temperature generally associated with the areas in which spark plugs are located, and can be applied to contacts as well (because the contact pressure is sufficient to penetrate the grease film). Doing so on such high-pressure contact surfaces between different metals has the further advantage of sealing the contact area against electrolytes that might cause rapid deterioration of the metals by galvanic corrosion.