There's quite a few cars on the road that seem to have more trouble with oil consumption. The GM 3.5s were/are bad about using more oil than they should. Not all of them are too bad...but I can think of several off hand that used 1qt/1000 miles while under 50,000 miles. I remember one customer came in after a couple thousand miles pretty upset thinking that we didn't fill his new car full of oil. He was two quarts down and blamed us for it. We refilled and he came back in another 1000 miles for an oil change, 1 quart down. He then apologized because he had been watching his oil more closely this time around and realized we were filling his car up. I think it was an 07 Impala 3.5 and this was probably around 2009 when this incident happened. I can think of a couple Malibus and Monte Carlo with almost the exact same thing. Customers who were always on time with maintenance with fairly new cars.
Even my mom's Malibu uses more oil than I feel it should. I change it every 5-6k miles with Napa Synthetic and it uses couple quarts or so. Strangely enough, 5-30 it uses nearly 4 quarts, but with 10-30 it uses about 2. I bought a bunch of 5 and 10 30 back with I had a 01 Monte Carlo and my 96 Grand Prix, so I had a bunch of 10-30 I put in just because it was there and it was summer. Thats when we noticed decrease in consumption...I've stuck with 10-30 ever since and it's stayed at 2 quarts.
Now my 96 uses about a quart every 6k miles...it's at 220k miles now. Something seems pretty backwards about this picture. All of these cars I'm talking about have not been neglected.