There have been no negative reports of the Wellman's as of this time. I doubt many are using them though. Of those who are, they have not had a problem yet. I figure since a set of glow plugs is about the same as a fill up these days, why try to go cheap? Glow plugs as a rule, are very reliable when controlled properly. Actually, I think they are really amazing. Have you ever taken one and hooked up up on a bench? That tip glows WHITE hot! I mean it is so hot, and so bright that you can't really look at it with the naked eye. And it can do that over and over again. My hat is off to the people who invented and designed them. They really are amazing. When you consider what they do, it's no wonder if they are held on too long, or are not made of the absolute best materials and construction, that things can go awry.