Axiom Home Page Forums General Discussion The Water Cooler mechanics or spark plug change experienced???

I don't think he was saying that the WD-40 would hurt anything itself, but it's tendency to loosen junk could create a problem when the plug is removed; that junk could fall down into the engine.

Also when installing plugs, I use anti-seize on the threads--as it a good idea when any two dissimilar metals are screwed together. This prevents galling when the plugs are next removed (I've seen pieces of an aluminum head stuck between the threads of a spark plug). And remember, the plugs don't need to be torqued to 150 ft lbs. The spec I use is to tighten them until the wrench handle has enough resistance to slip between a tightly squeezed middle-finger and thumb, then give it a quarter turn more (see the owners manual for actual torque specs).