Toyota branded synthetic oil is from ExxonMobil.

I doubt the Toyota 0W20 product is chemically identical to the Mobil 1 0W20, but should perform very well nevertheless. I suspect that the Toyota branded version might be built "lesser" compared to the Mobil 1 0W20 due to Toyota's rather short service intervals. My local dealership sells Toyota 0W20 for $2.99/qt when on sale, about half the cost of Mobil 1 0W20, so I'm not complaining...

I talked to an oil blender and he said that it's difficult to build a 0W20 oil without using mostly Grp III base oils anyway, so the oil is probably "mostly synthetic." The question is just whether or not the oil contains ExxonMobil's "top-of-the-line" additive package (which their Mobil 1 products do), but my suspicion is no, as it isn't needed in this case.