The discussion isn't about 35,000 mile oil? The discussion was about SSO 0W30 being specd for engines calling for a 20 grade oil. Only a fool with a new car and a warranty would use oil for 35,000 miles. RL doesn't make those claims, but if the oil is at fault I'd rather have them in my corner, in the grade the mfg calls for, not something they don't recommend.
Have a look at some UOA's where the TBN of SSO is shot long before 35,000 miles. Remember this isn't a prefect world. How about those filters that can't make the distance, they got caught with their shorts down on that didn't they?
Ford doesn't spec 30 grade oil for all their 2010 engines, most are probably calling for a 20 grade. Amsoil is the only company that lists a 30 grade oil for Ford and Chrylser apps calling for 20 grade oils.
Show me proof where FORD says it is OK to use a 30 grade oil instead of a 20 grade oil in the US for an engine calling specifically for a 20 grade oil. Seems Mobil got it right in your example.
Remember Amsoil can say anything they want about ASM and SSO it doesn't have the API approval, and don't have to answer to them. Oh yea they do claim to meet or exceed it though, they just didn't want to pay.
I'll take my chances with RL, on Dave's word alone.