My experience has been the same as trixers... In R/c Cars Planes, and 2 stroke dirtbikes. A rich engine will kill your engine faster than a lean one. My ST hasn't killed a plug in 8 gallons.. I haven't changed it either.. The element still looks great and I'm not running it lean, but get some smoke out of it.. I don't use a tach or anything, just tune for good transition and good top end.