I've acquired a 2010 Buick Lucerne with 34000 miles on it. Great ride. But can someone explain how or why they designed this engine to only take 4 quarts of oil? Really? That just doesn't seem like much especially if you are following the oil life monitor which can sometimes extend drain intervals.
My 84' Pontiac held 3-1/2 quarts with the filter. It managed to reach 300k before dying of rust.
I always bought name-brand oil and changed it every 3k. But the filters I chose for it were economy priced Puro Classics or Orange Can. That dipstick never read more than a half-quart low.
Use good oil and keep the dipstick level at full. Sleep well.