I usually buy 4 gallons, but it only takes 2 1/2 - 3 in my trailer , which is similar to yours. I would rather have a little extra than to get halfway through winterizing and run out.
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Dan-Retired California Firefighter/EMT
Shawn-Musician/Entrepreneur/Wine Expert
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package
4pt Equal-i-zer WDH and 1828lbs of payload capacity
Type "winterizing" in the search section up there.
You will have reading and more to reach satiety.
Don't forget to use "plumbing" antifreeze that you can recover through the low points at springtime and reuse.
Plumbing antifreeze and RV antifreeze is the same thing. RV antifreeze is used in homemade solar hot water systems.
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Richard & Jill
2014 Flagstaff 832IKBS Classic Super Lite
2018 Silverado 1500 Crew Cab Z71 4WD All Star Edition
Camping since 1989, Seasonal since 2000.
Car Shredder Op/Tech, Scrap Metal Recycling - retired
On my 26DBH I buy 2 gallons. I also installed a winterizing kit. Takes me about 20 minutes for the whole process. Oh, don’t forget your black tank flush. I have a manual pump for that.
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2016 Grey Wolf 26DBH
Ram 2500 5.7 Hemi 4WD