synthetic = good choice
NO real opinion on Mobil synthetic versus any other synthetic-
but synthetic in general while costing more provides a small measure of additional protection -for example if the diff were to spring a leak without you noticing it.
You are not going to be able to run it dry obviously-but the synthetic stickiness to the parts will give some additional protection that would drip off immediately with the dino based products.
I run synthetics everywhere possible.
Oil and transfer cases.