The workhorse, at the heart of smooth-running engines around the world. -OEM Quality -Triple-Gasket Sealing Process -Consistent Performance -Plug of Choice in Millions of Vehicles -The thermal grade of the spark plug is of prime importance with tuning kits. If the wrong grade is used the kit will overheat or the spark plug will foul. A hotter spark plug transfers more heat to the cylinder head which may lead to piston seizures.
The heat rating of each NGK spark plug is indicated by a number; lower numbers indicate a hotter type, higher numbers indicate a colder type.