Driving with Grey tank full

[jps23579]

Its my Understanding that -> A GOOD many fresh water tanks actually have baffles or "holed' walls in them so as to limit the sloshing of water in them, whereas the less expensive Grey & Black holding tanks have none in them and are designed that way so that they drain quickly.  As for mileage ..Traveling to the mountains might best be done empty. Whereas on the way back down additional weight could be beneficial .. Provided you have good brakes..LOL  IE Grade plays a big role .  JP