[coolhandcountry]

Diff oil in a rc does different than diff oil in a 1:1.
Diff oil in a 1;1 lubricates the enter rear end axle bearings and all.
Diff oil in a rc acts more like a lubricate just for the spyder gears.
It adds resistance in between the spyder gears.
The thicker the oil the more resistance you have.
The thickness would depend on alot. Weight, tire, traction, driving style, and few others.
The oil has to be based by you. Kind of a trial and error thing.