The thing I did to my 2012 Regal GS this week is I sold it. I sold it because the motor is blown, and I am not sinking another $6k into this car. My repair shop was in the process of repairing a defective injector, which had resulted in that cylinder being full of gas (liquids are not compressible), which is what probably did the engine in. While the compression test looked good, and the motor still could start, it made terrible noises and would need replacement. I bought this car with 72k miles on it in May 2018 and it ended up having somewhere in the 10x K mile range at the end. My Regal had nice road handling, looked cool, had incredible power, and I enjoyed driving a stick. But all the maintenance issues, particularly for things like replacing the headlight assemblies which should not have ever been needed, made it be not be a fun experience for me. So it was time to move on.
I really appreciate the help that many of you have offered on this board. For the headlight assembly replacement in particular advice from others helped me find a much better replacement product than otherwise, and find it sooner, and helped me understand how to install them in the simplest and lowest-risk way. I wish you all the best experience with your peculiar and sometimes wonderful Buick Regals.
One of the things I did on my 2012 Regal GS was to replace all 4 wheels and tires, using 18" wheels so I could have tires with almost-normal sidewalls that would not blow out so easily. I still have the 4 GS wheels and tires. I of those 4 GS wheel rims is bent - driveable at local driving speeds but something you would want to fix, and there is curb scarring on at least some of the rims. If these would be useful to someone and can pick them up in person (north-central NJ), make me a reasonable offer via PM.