The OEM two-piece plugs I installed think I had them in about a year and a half. I also used some copper anti-seize that time so that likely helped. The last plug on the passenger side was still difficult to get out (thought I was going to break it even with the impact gun). According to the mechanic in the video the premise for using the impact is to use an adjustable model and tease the plugs out using the impact action vice full power.
A couple of maintenance routines I now follow are to clean out the carbon buildup from the plug holes with a round wire brush, use anti-seize where recommended and check them at least once a year (spring). First set of one-piece plugs I tried were Champion. They lasted about 2 years (maybe 20 - 30K). Now I'm trying Brisk plugs. They run great. Not sure how long they'll last though. I just installed them a couple of months ago so I'll check them in the spring to see how they look.
Not an expert on two piece plugs but looking at one not sure why a small weld cannot be added at the point where the shells meet. Would the welding compromise the plug in some way (electrical breakdown, warp the body in the some way, not enough room, or just not worth the extra effort)?
