The champion spark plugs ARE coated from the factory, but if you must, don't use much, just a smidget, like the amount you could put on the end of a pencil...don't get any on your aluminum or stainless...There is really no need, IMO, if you change your plugs every 12,000 to 15,000 miles, like most of us who are anal retentive...and remember you are installing them into an aluminum block, so snug em, and then a quarter turn and that's it...