Re: o2 dumby plugs
Some people use them to plug the holes while doing top end work or pulling an engine. Avoids breaking a real plug.
They can also be used to check for clearance when changing stroke, pistons and heads.
If you shave your heads or deck you might need to use a different plug.
Avoids mashing a real plug.
2006 4.0 5 spd auto 4x4 Super Cab
BF Goodrich Commercial Traction T/A's
Royal Purple Throughout
Alpine Head Unit with some Infinity Noisy Stuff