Which Prime Guard RV & Marine Antifreeze Is Best For Jayco Eagle Fifth Wheel In Michigan Winter?

Published 10/20/2025

Products Featured in This Question

Prime Guard RV & Marine Antifreeze -50°F Burst Protection - Ethanol-Based - 1 Gal - 6 Jugs

(3)

$89.75

Prime Guard Premium RV & Marine Antifreeze -100°F Burst Protection - 1 Gal - 6 Jugs

(4)

$185.33

Question:

I’ve got a 2018 Jayco Eagle fifth wheel that spends winters in Michigan. Will the ethanol-based Prime Guard be enough protection for me or should I go with something stronger?

asked by: Brian

Expert Reply:

Brian, for Michigan winters you’re right at the edge of what the ethanol-based Prime Guard # PG56ZR is built for. It gives you –50°F burst protection, which is plenty for typical storage, but if you see long subzero stretches, I’d bump up to the –100°F # PG96ZR. The nice thing is both formulas flush easily in the spring, so you can swap without any hassle.

I also would strongly recommend the -100F option since it is alcohol and glycerin free, meaning the seals will stay protected longer.

How cold does your storage barn usually get in January?

expert reply by: Andrew N

Brian

10/20/2025

If temps here never get anywhere close to –50°F, why would I still need the –100° one?

Andrew N.

10/20/2025

@Brian Good question. The “–50°F” on the jug actually refers to burst protection, not the temperature where it stays liquid. The –50°F mix can start to slush around 10–20°F, which is fine short term, but if your rig sits for weeks in those temps, the thicker fluid doesn’t circulate as well. The # PG96ZR stays flowable longer, so fittings and valves get full coverage. It’s less about record lows and more about how long the cold hangs around. Do you keep your Cougar in a heated barn or open storage? That’ll tell us which one’s the better fit for you.