If you are not towing with this vehicle and want your best fuel economy, I would stay away from the 140 oils. Especially since it is mostly used for commuting. Those recommendations are probably "geared" towards non-synthetic oils. I would be inclined to use a quality 75W-90 synthetic that is formulated for limited slip. Mobil 1, amsoil, Schaeffers, Redline, Royal Purple are several that come to mind.
Going with a synthetic is a no-brainer for me since these axles rarely hold more than a few quarts and do not require constant service like engine oil. The synthetics or blends will hold up better (Viscosity and oxidation) in the heat and flow faster when it gets really cold. The thickest oil I would use in your app would be Amsoil 75W-110, which is right in the middle. RP Max Gear is also on the heavier end of the 90 grade.
A synthetic blend would be another good, but less expensive option, and can be found at most auto parts stores. Pick up a bottle of limited Slip additive while you are there-you will probably need to add some or all of it to eliminate LS clutch chatter on turns.