Just be careful....on my RS23V0A, I change plugs ftom underneath the car using a six (6) point combination wrench just the box end. Driver's side is manageable from the top side but the passenger side is impossible from the top. As suggested, use PB Blaster or Kroil but with a cold engine. Using a box end combination wrench lessens the possibility of breaking the porcelain, as the effort will be directly applied to the hex part of the plug and depending on the brand of the plug, some are more robust than others, specifically Autolite. The newer Champion plugs with a cold press area directly below the hex are susceptible to breaking.
Several years ago I was changing plugs on a Ford 406 engine with 18mm taper seat plugs with a 1/2" drive deep well 13/16" hex spark plug socket and the last one on the right side seemed more stubborn than the others, so I applied more effort on the ratchet handle....result the plug broke off right below the hex, with the threaded end stuck in the head, the porcelain part came out in one piece, leaving a hollow slug in the head......many expletives....OH WELL....soaked the shell with liquid wrench, grabbed an EZ-out, with a hex nut pressed on the end and screwed it in the hollow slug of the shell and applied much torque to the wrench with the understanding that if it breaks, the head must come off or ...... but the wrench Gods were smiling and the plug shell came out, squeaking. Morale of STORY....ALWAYS use a dab of anti-seize on the spark plug threads ...ALWAYS. And just snug the new plug in...no need to crush it in, just 10-15 pound feet of torque will be sufficient.....Just my opinion of course..
BOB RENTON
