[JRTJH]

Nope. I pour the olive oil down the toilet after all the tanks are empty. It coats part of the bottom of the tank and flows to the rubber seals where it sits all winter. I do the same with the two gray tanks by removing the P trap and pouring the oil down the "straight pipe into the tank"... Then I reconnect the P traps and pour enough antifreeze into them to make a liquid seal so odors won't flow back up into the trailer.