I use 80W-90 in all gear applications except when there is an actuator involved (such as an ADD system), and then I use 75W-90 so that the actuator can do its job easier when it's cold. I used Mobil 1. I consider both of the ones you mentioned overpriced. I doubt that you will see any difference in performance no matter what gear oil brand you use. I just used a synthetic to increase the drain interval.