I was recently told by a marine mechanic that I should switch from the Champion UL-18V surface gap plugs to a L77-JC4 plug with a .042 gap. He told me that "This plug fixes a problem with the newer unleaded fuels that the 89 year model engines cannot overcome otherwise. It vastly improves idling, low speed (eliminates the rumble & shudder) and burns cleaner at high speed. " However, I read a thread on this forum that says you should only use surface gap plugs because conventional gap plugs can burn a hole in the cylinder? I definitely don't want to do that. Which plugs should I be using? Can surface gap plugs perform adequately with today's fuel and will conventional gap plugs really burn a hole in the cylnder? Thanks.