ORIGINAL: Chris_RC
DO NOT get the OS plugs. Their taper is different and will ruin the head button. Say you got an engine without a glow plug, you could run an OS IF you never switch back. OS's also have a shorter body which means you won't get the right compression/performance with OS plugs.
Chris: Gotta say that I've never had an issue like that. Very interesting though. I interchange different brands of plugs (for no specific reason) - - but I have to say that OS is on the top of my list.