This unit really works. My new 2018 Silverado 1500 ("e" model) was running well before I plugged it in the OBDII socket, but I wanted the option of disabling this V8-V4 mode because of what had happened to my friend's 2011 Sierra 1500 (excessive oil consumption between scheduled oil changes due to worn rings on an otherwise meticulously maintained truck. This was traced to a lack of proper lubrication in V4 mode, an issue supposedly fixed since in the newer models). I just couln't afford to take any chances at having to go through an engine disassembly so soon in my truck's life. I mean, how long have they been messing with V8s? They should have left these engines alone instead of messing with cylinders 1, 4, 6, and 7. Since I do mostly highway trips, my mileage has actually improved, not by much, but it shouldn't have if you believe the GM hype. You really have to wonder why all this V8-V4 complexity was added to a perfectly good V8 if as, in my case, my mileage improved!!! The ONLY thing I miss at times (easily fixed by shutting down the truck and just unplugging it from the OBDII socket) is some engine compression braking in hills from the V4 mode. It helped me maintain a set cruise speed going down some hills with a light 2000 pound trailer load, and the fact that the engine no longer shuts off at stops or red lights (the "e" model has the Lithium battery pack and induction motor to spool up the engine under these conditions but it won't do any of that while this particular unit is plugged in). Other than that, I have the V8 I expected now, the mileage is fine and hopefully I won't have issues with failing parts in cylinders 1,4,6 and 7. The added complexities of these otherwise old V8's should be a cause for concern. They use a special camshaft ground differently just for cylinders 1,4,6 and 7, they have a higher-volume oil pump, and a pressure relief valve to handle the incessant oil/computer controlled operations of the intake and exhaust valves in these 4 cylinders and this device just stops all this from happening without reprogramming anything. I could be wrong of course, but I think the pressure relief valve should have no issues handling the changes for the life of the engine. The rest is literally put to sleep while this device is plugged in.If you want to take your truck in for maintenance, say while it is still under warranty, just remove it before going into the stealer. They will never know. Hopefully I'll never have to go in for expensive repairs due to failures with cylinders 1,4,6 and 7. Make sure you get this device with the latest firmware as it is now totally stealthy to Onstar's big brother monthly reporting. Range Technology has done its homework. I don't work for them, I'm just a happy customer and would recommend this to anyone just wanting back the V8 truck they thought they bought.