I think that de thickness of the fluid cannot hold the forces that de engine produces. Besides, when de fluid get warmer, due to driving, it gets less thick.
Last week I drove the truck with only front-wheel-drive. It is getting nowhere. Only wheelspin. Isn't it with the gears installed the same, you get power to the wheels with the lowest traction (the front wheels). Steering is beter, but mine steers allready good (10kgs servo installed for steering)
Braking is also good, I installed the 5kgs servo (was installed for the gearbox!!) to the trotthle/brake linkage and now it brakes very wel.

Gr. Emile Koole