How much antifreeze to purchase?

[New England Weekender]

Not sure if this warrants a post but I did search and not find an answer.

I'm currently at work and plan to start winterizing my RV today after lunch. I had planned to pickup antifreeze on my ride home as I have a Walmart, Home Depot, Camper's World, and a local RV dealer all within a few mins of my job... but I forgot to check my manual to see how many gallons I'll need. I've never done this previously, so for the first time, I'm watching Youtube videos on what to blow out with the air chuck as well as where/how to add the antifreeze. Any idea how many gallons I should buy? Is 1 plenty or should I buy 5 or 6 knowing whatever I don't use, I can use next year.

If it matters, the trailer has 1 full bathroom, 1 kitchen sink, 2 exterior spray ports, 1 additional gray tank for the kitchen sink and I believe that's all that may be relevant. Thank you.

 

[gregrc75]

I usually use about 3 gallons. I also pour a little in each sink trap, and also cover the seal of the toilet.
I have a tankless hot water heater but it really isn't much different if you bypass your hot water heater if it is not tankless.

 

[Hoopy Frood]

Our Momentum has the rear bathroom, front bathroom with shower, two spray ports, and the kitchen sink. I use about 3 1/2 gallons. I don't blow out the lines.

 

[lorend]

I have the same configuration of tanks and fixtures as you do on my 30ft fifth wheel. I bypass my water heater and blow out with air the same as you are suggesting. I use right at two gallons of antifreeze every time I winterize. Not knowing which rig you have it might be a little different. I am also careful and make sure to get the propylene glycol rather than the ethyl alcohol.

 

[Soundsailor]

+1 - 3 gallons