I own a dealership, so it's usually the lowest synthetic that fulfills whatever requirements are needed for the vehicle. Supertech is great, but we also use Pennzoil, Shell Car & Truck, and Mobil 1 depending on the incentives available.
As an aside if you ever sell an older vehicle and use synthetic oil, it's a big plus if you mention it. Most folks just want a ride that will keep them on the road and the quality of your upkeep makes a huge difference when it comes to price and the need to negotiate.
I switched to a blend this OCI (Pennzoil High Mileage) after running only synthetics in this car for 60k miles, and I think Im going to continue on this path. I do 5,000 mile changes, and I'm a thickie too, so I don't see much point in running a synthetic for short intervals. Might try GTX HM next.
On the shelf is:
PP Euro 0w40
QSFS UP 5w30
QSFS Euro 5w40
Havoline Lifelong 10w30
Delo XSP 15w40
In the vehicles are M1 5w40, Total Quartz 9000 5w40 & QSFS Euro 5w40 and Motul Xclean 5w40.
QS will probably be my preference but will buy some more Total and Motul as they seem pretty decent and not overly expensive. PP is bought during rebate season and Delo was found on clearance.
After making the rounds from QSUD , PPPP , Castrol , Valvoline and M1 5W30 / 0W20 synthetics - I'm down to Valvoline (Advanced / EP) in my oil stash and next will try the newer M1 Tripple action synthetic oils . The little Kia 2.0L Nu MPI engine and the Corolla 1.8L MPI engines run clean and don't burn a drop of oil at normal OCI's . Conversely , the Hyundai 2.4L GDI engine is one dirty , soot producing , oil burning piece of work that is on a 4,000 mile OCI regiment (for good reason !)