29-08-15, 03:32 PM
I have been a mechanic for 30 years & I did say use it lightly & not near the washer as it doesn't compress but it does stop alloy corrosion! I probably change 60 plus plugs a week & in 99.9% of cases I wouldn't use anything on the threads & don't physically check the gap tho I do look at the gap, don't ever presume the gap is correct cos' the plug is new, plenty of boxes of plugs get dropped! If I ever struggle to remove a plug or snap a plug I will clean the thread, blow the crap out, clean it again then run the chaser back in with a very tiny amount of copper grease (& I do mean tiny amount) before inserting a new plug! You shouldn't use it anywhere near hubs, wheel studs etc as it doesn't compress & messes with torque settings. I have lost count of the amount of times people have complained about warped discs & it is caused by copper grease on hub faces! Iridium plugs do give a cleaner spark, will work with a wider gap using less voltage etc & do last longer but they should still be removed, checked & cleaned! as people do fit & forget they have been known to suffer from tracking on the porcelain.