You'll be fine MAC. I just saw an engine where QS was pretty much all they used and it was like someone poured tar in the engine after X number of thousand miles (like life of engine) but I've never seen oil sludge up like it was.
I used to use Castrol, it's a good oil. But coming from a family where my step-father was in the oil business. If the oil has the API certifications and they match what you're supposed to use for your car, then usually you'll be fine. I've used Wallyworld (supertech) oil for the past 4 1/2 years and had ZERO problems. Heck I even use the ST filters. I've put over 45,000 miles on my car and again, ZERO problems. Just change your oil regularly. That's the key. Also, NEVER let it run more than a quart low. I've heard our cars love spinning bearings when we have really low or dirty oil.
