On my E Maxx I have spools F/R no lube, On my T Maxx it is what ever is in there stock because I haven't had to take it apart yet, the following was taken from a tunning guide on the Traxxas web site, "Normally, I use 50,000wt in the rear, and 30,000 in the front. The heavier fluid in the back gives me a little more “on throttle” steering, which is desirable for a 4WD monster truck when you need to get around sharp turns. Experiment with different thicknesses to see what works best for your driving style/conditions." hope this helps...