Antifreeze To Winterize 2021 Keystone Cougar Parked In Northern Illinois
Published 10/20/2025
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Question:
I’ve got a 2021 Keystone Cougar that stays parked in northern Illinois. Which Prime Guard antifreeze should I use to winterize. the –50° or the –100°?
asked by: Mark
Expert Reply:
Mark, for Illinois you’re right on the border between the –50°F and –100°F options. The standard # PG56ZR ethanol-based blend will usually handle normal Midwest winters just fine, but if your rig sits in unheated storage for weeks of deep freeze, step up to the premium # PG96ZR for peace of mind. It costs a little more but adds serious protection against those random cold snaps.
Do you store indoors or outside over winter?
Product Page this Question was Asked From
Prime Guard RV & Marine Antifreeze -50°F Burst Protection - Ethanol-Based - 1 Gal - 6 Jugs
- RV Fresh Water
- Winterize
- Antifreeze
- Prime Guard
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