i just winterized my 40 ft fleetwood excursion with washer/dryer and ice maker/water supply. i found how much i needed depended on several things. 1. how fast i turned off the washer--2. did i put the topper on the water filter or fill the whole container. 3 how much did i spill/waste. it took me a little more than 2.5 for the pink stuff to be in all the pipes. i then used another gallon to pour down each sink(i have 3) and some in each toilet.(i have 2). i then leave a gallon in the bathroom in case i deciede to take the mh out and someone wants to use the toilet. they will flush by using the gallon of pink stuff. it is a much easier job with a buddy to change gallons as they empty. i had a helper and was done under an hour(and i am no mechanic). it is sorta fun and pretty easy