How often should it be done? I just opened mine up and it didn't look like the case was full. It looked completely empty although it was still lubed. Is this ok?
if your on about the front and rear diffs then they should be packed.
slash revo vxl x4 rally x2 ped 2wd slash vxl rus
The fluid level decrease over the time, I just did mines an filled them about 75%, if you do 100% when you tight the both ends a lot of the fluid will come out.