2010 HO v6 burning oil like crazy, opinions needed

So I've had my 2010 SXT since March 2012, I got it at just over 18,000km. It now has almost 70,000km. It's eating oil like crazy. I tried the valvoline fully syn for high mileage (I was tricked into thinking it was for extended miles, not cars with high miles), and it burned down to 1cm below the min line on my dipstick in less than 2000km. Topped it up and ordered my usual Quantum Blue. Had that put in, and the place tried to tell me I was due for a change (which wasn't true, I went in at 4000km ish, instead of the 5000km they told me). The Quantum Blue has done slightly better, but I've topped it up twice now.

My car never did this before, nothings changed. Same tune, same gas station, same wheels and tires..... should I sell this car before something catastrophic happens? It's my first car, so I'm kind of attached to it, it's given me no other real trouble...

What do you guys think?:frown2: