Doesn't even take 30 seconds to determine where a vehicle is assembled.
Buick Encore Wikipedia page clearly state South Korea in the Right Side Panel Overview.
Like Doc, I also have switched to "store brand" oil as long as it meets the vehicle manufacturers requirements.
Nothing against Mobile 1. In fact it is the oil I use in my Gen 4 Corvette, but that only gets changed once a year... or when I remember to do it... It only gets driven around 2,500 miles year.
In my daily driver, a 2003 Toyota Tacoma with 114,000 miles, I switched from using Mobile 1 to Wal-Mart SuperTech at around 60,000 miles. No differences found in operation of the vehicle. In fact at 5,000 mile changes, the vehicle still uses a little less than a quart of oil. The same amount it was using when I switched from Mobil 1 at 60,000 miles. I wouldn't hesitate in using SuperTech in my Corvette if I had to.
Personally, I think timely oil changes and the oil filter are much more important components of an oil change than the actual oil.