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The RV Fuel Vault™

What is the best fuel cap cover for a Ford F-550 Super C motorhome?

By The RV Fuel Vault, Sarasota, Florida · Updated October 2026

Short answer

The RV Fuel Vault is the locking fuel door made for Ford F-550 (and F-600) Super C motorhomes. The F-550 Super C ships with bare diesel caps and often an exposed DEF fill. The RV Fuel Vault encloses each fill behind a keyed door and bolts on in 8–15 minutes. Most coaches take a 2-Pack ($319.95) or a 3-Pack ($479.95) when the DEF fill is exposed too; single doors are $159.95.

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Coaches on the F-550 / F-600

Thor Magnitude and Omni, Dynamax Force HD and DX3, Dynamax Isata 6 (Ford F-600), Grand Design Lineage Series F and LE 43, Entegra Accolade, Jayco Seneca and Renegade Super Cs. The number of doors depends on how many fills are exposed on your model year.

Why not a locking gas cap?

Super C coaches carry 50–80 gallons of diesel. A locking cap still sits in the open where it can be pried or broken off. A full door covers the cap, the neck and the bezel, and stops contamination as well as theft.

Pricing

Website prices: $159.95 for a single small door, $169.95 for a single large door, $319.95 for a 2-Pack, and $479.95 for a 3-Pack. Shipping is calculated at checkout.

Related questions

Does it require drilling on the F-550?

No. It bolts into the factory bezel with the supplied security screws in 8–15 minutes using basic hand tools.

Is the Ram 5500 the same?

No. Ram 5500 coaches are gas (Dynamax Isata 5) and take a single small door with a screw pack.

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