RE: How waterproof is the HPI Baja 5SC?
Batteries are a little difficult but one thing I've seen use is really heavy diff oil. Like 100k or above. What I've seen done is opening the actual electronic thing you want waterproof, then spray it with WD40, then let the diff oil drip on them and cover them back up and wipe off the excess oil. Then plastidip the outside. They sell this stuff at just about any hardware stuff. It comes in a can and its like a liquid rubber. You dip what you want into it, take it out and let it dry. Takes about a minute or so.