I think the brand name is up to the dealer, beyond the fact that it has to meet min factory specs. I have a 4Runner but I do the oil changes. The dealer, for me, is just there to do warranty work, if needed. Any service I can't or don't want to do is done by an independent shop that has factory trained mechanics in my area.
As a side note, most API conventional oils are about the same, so the oil they pick might be the one they can turn the most profit on. No matter what they say, it's economics, not any factual knowledge they may have that makes the choice.