Thanks for the link, this helps confirm that the 5w-30 oil is a better option than the 0w-20 from the factory.Yes, you are partly correct, the US created the Tier 3 program which considers the vehicle and its fuel as an integrated system to reduce the impacts of motor vehicles on air quality and public health. The program set new vehicle emissions standards and lowered the sulfur content of gasoline to a maximum of 10ppm beginning in 2017. The program grew out of a Clean Air Act, and ever since 2017 our fuel quality standards have been in line with those in Europe, but not before then. Before this change had occurred, oil used in the US often times used additional alkaline additives in order to combat the build-up of acids in a lubricant as it breaks down. Refer to the Total Base Number (TBN), which is a measure of alkaline concentration present in a lubricant. The higher the TBN, the more protection you get from sulfur or other acid compounds. You'll look on the tech specs of any given oil to find those numbers. Above 8.5 TBN provides decent protection in countries with 10ppm or fewer sulfur content in the gasoline. Most all engine oils are formulated with >8.5 TBN. Now back to CAFE and the viscosity of the oil, those things are directly related. To play it safe, any oil used in the B58 engine should at the very minimum have 3.5 cP or greater High-Temperature/High-Shear Viscosity rating measured using ASTM D5481. For B58 Turbo engine Bimmer world recommends 5w-30, 10w-40, 5w-40 or 0w-30.
The link also provides some interesting comments on driving habits to avoid oil sludge and build-up, basically hinting if you drive in low RPM often (not in sport mode) it's probably not good for your engine.
Luckily my dealer has two qualified Supra techs with 25+ years experience each. Supras don't go through the quick change lane and after a conversation with the service manager to school up his parts people, they had the correct oil in stock ahead of my appointment... He was kind of pissed that his people had plenty of filters and such but no oil. He actually thanked me for getting them up to speed.... I'll still do my own after the freebies though.
You can look up exactly what part numbers they used to change you oil. Don't think they are gonna go as far as falsifying records to stick you with the wrong oil (I also confirmed part numbers that will be using before bringing my car in).