Spot on, use this stuff for the gears (light smear on the flank of a couple of teeth, then rotate the gearbox so it gets to all the teeth) and the Finish Line Cross Country synthetic on the rolling element (ball) bearings (a couple of small drops per bearing). Use an Associated diff grease on the diff balls (only enough to coat the ball, no more!) and a black graphite grease on the thrust race.
Make sure that you only use enough to lubricate the direct area. This is a small space, so if the lubes migrate from one area to the other, you don't get the proper performance from the lube you've chosen. Common mistakes are to drown the ball bearings, slap diff grease all over the place and have a whole pot of ceramic grease (I exaggerate for effect!) in the gearbox. Little in the right place, and check often, is the best policy.
Lots of people are fans of Royal Oil. Think of it this way - would you put 3-in-1 oil, or sewing machine oil, in your car engine? No, so stick to a proper synthetic oil in your RC bearings. HTH
