Actually, no they don't have a lifetime warranty and Magnecor wouldn't replace them for free even though 2 sets couldn't last a month each without constant misfiring with stock plugs. They were happy to sell me a new set for $50, though. Even refused to return my bad set to me. That was 4 years ago. I get the Motorcraft wires for $45 a set at the dealer and replace them when I change plugs.