I use QS conventional, no problems with it at all, my engine runs very smooth and quiet and I get the same MPG and power with QS as I did on Valvoline conventional. Consumption is the same too, about maybe 1/3 of a quart in 2,000 miles.
I bought 3 cases of QS Advanced Durability 10W30 last year when Advance and Kmart had it on sale. My current stash cost me about $2.16 per quart.
QS is a great oil, has a good quality add pack and areound here it is usually on sale for a good price per quart or as part of an oil and filter deal at one store or another most of the time. I will not use Mobil oil or Mobil gas, but I have my own reasons for it and they don't belong here.