Changed the glow plugs in my LBZ Duramax Diesel and learned a few things. First, why did I jump into this project? Whenever it was cold out (which is often here in Michigan) the glow plug would come on and when it went away the Check Engine light would stay on. So I pulled out my spade tuner and read the code which was ECM P0672. Review what the code is its defined basically everywhere as a semi generic code but with some specifics like what cylinder to troubleshoot So which one is the #2 Not that it really matters since when you are changing them its always recommended that you replace all of them. Passenger side (1,3,5,7) easier to access than drivers side (2,4,6,8) since nothing is blocking access to the glow plugs on the passenger side. I started the drivers side and cylinder 2 was blocked by intake (easy, just remove on top and it gives you enough room to get around it) and cylinder 4 was blocked by the steering shaft. There is a bolt that holds it together, just take that out (don't let it spin on ya or your steering wheel won't be lined up). I purchased AC-Delco Glow Plugs (8 of them was $162). Now what I was disappointed on was I saw all the YouTube videos showing how bad Beru Glow Plugs are and said to myself, I'm not buying that crap, I'll stick with factory AC Delco and come to find out that AC Delco glow plugs are Beru made in Germany. Dang it! Went to the passenger side and discovered all those turned out to be DieselRX glow plugs and who ever put them in did not put any anti-seeze and thats all kinds of bad. Steel Glow Plugs on Aluminum block and they did NOT want to come out. I was worried of breaking them in the block but was lucky to be able to remove them and replace them with the AC-Delco glow plugs. Of course bad luck kept coming with a broken glow plug wire on #1 so had to do some wiring (which I can't stand having something not factory but replacing a glow plug wiring hardness looked to be a pain in the butt so we'll see how well the patch does.) Cylinder 3 & 5 when those glow plugs were removed, were coated in oil but its been said thats okay/normal. Apparantly there is a pit in which the glow plug sits and oil collects down in that pit while the glow plug is in place. Once you pull out the glow plug the oil will drain into the cylinder, which is fine, you will burn the oil off once you start and drive your truck. I took a photo of what it looks like on these DieselRX glow plugs. So now no more check engine light.