Mobil one synthetic too. It's such a small difference in price for the application size there's no reason not to use synthetic.
Well, save one. If a bike has been sitting for a long time (decades for many of the CX's and GL's out there), the diff should have a good flush. Best way to do this is to buy the cheapest stuff you can find, and change it every couple hundred miles a couple of times. When the fluid drains the same color it went in, then you can do the swap over to full synthetic.