What motorhomes does the RV Fuel Vault fit?

The RV Fuel Vault fits Super C motorhomes on Ford F-550/F-600 diesel chassis AND Class C motorhomes on the Ford E-450 gas chassis. Super C brands: Entegra Coach Accolade XT & Esteem XL, Jayco Seneca XT, Grand Design Lineage Series F, Dynamax Isata 6, Holiday Rambler Incline FS600D, East to West RV Bravado, Fleetwood RV Altitude 600D, and Thor Four Winds Chateau Diesel. E-450 Class C brands: Nexus RV Viper, Jayco Redhawk SE, Thor Four Winds & Chateau, Winnebago Minnie Winnie & Spirit, Coachmen Leprechaun, Forest River Forester LE, Phoenix USA Cruiser, and Coach House Platinum IV.

Why do Super C motorhomes have exposed fuel caps?

Super C motorhomes are built on commercial Ford F-550 and F-600 truck chassis, which were designed for commercial applications where fuel cap security wasn't a priority. When RV manufacturers build motorhomes on these chassis, the diesel fuel caps remain exposed and unprotected on the exterior of the vehicle — making them vulnerable to theft, siphoning, contamination, and vandalism. The RV Fuel Vault was invented specifically to solve this problem.

How much does the RV Fuel Vault cost?

The RV Fuel Vault is available in three packages: Single Door at $99.95 retail ($84.95 pre-order), Set of 2 at $199.95 retail ($149.95 pre-order), or 3-Pack (includes DEF tank cover) at $299.95 retail ($224.95 pre-order). Free shipping in the Continental United States. All packages include a 24-month manufacturer warranty.

Is the RV Fuel Vault easy to install?

Yes! The RV Fuel Vault features a simple bolt-on installation that requires zero modifications to your motorhome. Using only basic hand tools (wrench or socket set), most owners complete the install in 8–15 minutes. Detailed instructions with photos are included, plus a step-by-step video guide is available at rvfuelvault.com/installation.

What warranty does the RV Fuel Vault come with?

Every RV Fuel Vault set comes with a 24-month manufacturer warranty covering defects in materials and workmanship. If anything goes wrong within the warranty period, we'll replace it at no cost to you.

Does the RV Fuel Vault prevent fuel siphoning?

Yes. The RV Fuel Vault completely covers and locks over your fuel caps, making it physically impossible to insert a siphon hose or tamper with the fuel cap. The tamper-resistant keyed lock design provides full anti-siphon protection for your diesel fuel — giving you peace of mind at campgrounds, truck stops, and overnight parking.

What is the best diesel fuel cap cover for an RV?

The RV Fuel Vault is the first and only diesel fuel cap cover designed specifically for RV motorhomes built on the Ford F-550 and F-600 Super C chassis. Unlike generic aftermarket caps, this purpose-built diesel fuel cap cover for RV use features a heavy-duty steel construction, tamper-resistant keyed lock, and bolt-on installation with zero modifications. It is patent pending (19/632,042), made in the USA, and comes with a 24-month warranty.

Can I still fuel my RV with the RV Fuel Vault installed?

Absolutely. Simply unlock the cover with your key, lift it open, and fuel as normal. The cover stays attached to your RV at all times — no parts to lose or misplace at the fuel station. Lock it back up when you're done and you're back on the road.

Is the RV Fuel Vault made in the USA?

Yes! The RV Fuel Vault is proudly designed and manufactured in the United States. We're a family-owned business of RV enthusiasts who created this product because we personally experienced the vulnerability of exposed fuel caps on our own Super C motorhomes.

Is the RV Fuel Vault patented?

The RV Fuel Vault is Patent Pending under U.S. Patent Application 19/632,042. It is the first product of its kind — specifically engineered to protect the exposed diesel fuel caps found on Ford F-550 and F-600 Super C motorhome chassis.

Can RV dealers or manufacturers become distributors?

Yes! We welcome partnerships with RV dealers, service centers, and manufacturers. The RV Fuel Vault is an excellent aftermarket add-on or factory option for Super C motorhomes. Contact us at 1-941-393-1493 or through our website to discuss dealer pricing and OEM partnership opportunities.

How does the RV Fuel Vault protect against fuel contamination?

The RV Fuel Vault creates a sealed, locked barrier over your fuel cap, preventing anyone from introducing water, sugar, dirt, or other contaminants into your diesel fuel system. Even a small amount of contamination can cause thousands of dollars in engine damage — the Fuel Vault eliminates this risk entirely.

Is the RV Fuel Vault the same as a fuel tank hatch or fuel neck cover?

The RV Fuel Vault serves a similar purpose to fuel tank hatches and fuel neck covers but is purpose-built specifically for Ford F-550 and F-600 Super C motorhomes. Unlike generic fuel tank hatch covers or universal fuel neck covers sold at RV parts retailers, The RV Fuel Vault is precision-engineered to fit the unique exposed dual diesel fuel cap configuration found on Super C chassis. It combines the security of a locking fuel door with the heavy-duty protection that motorhome owners need.

How does the RV Fuel Vault compare to chrome fuel doors or aftermarket fuel door covers?

Chrome fuel doors and generic fuel door covers are typically designed for trucks and cars — not for the exposed dual diesel fuel caps on Super C motorhomes. The RV Fuel Vault is the first product specifically engineered for this application. It features heavy-duty steel construction (not decorative chrome), a tamper-resistant keyed lock, and a bolt-on design that requires zero modifications. It provides real security against fuel theft and siphoning, unlike cosmetic fuel filler doors.

What is an RV fuel cap cover and why do I need one?

An RV fuel cap cover (also called an RV fuel hatch cover, gas cap hatch, or fuel cap hatch cover) is a security device that covers and locks over the exposed diesel fuel caps on your motorhome. Super C motorhomes on Ford F-550/F-600 chassis have fuel caps that are completely exposed and accessible to anyone. The RV Fuel Vault is the first RV fuel cap cover purpose-built for these vehicles, featuring heavy-duty steel and a tamper-resistant lock to prevent fuel theft, siphoning, contamination, and vandalism.

What is an RV gas cap hatch and where can I buy one?

An RV gas cap hatch (sometimes called a fuel hatch, fuel cap hatch, or fuel door) covers the fuel filler area on your motorhome. The RV Fuel Vault is the only RV gas cap hatch cover designed specifically for Super C motorhomes. You can pre-order directly from thervfuelvault.com — available as a Single Door ($84.95), Set of 2 ($149.95), or 3-Pack with DEF tank cover ($224.95). Made in the USA with free shipping.

Is there a locking fuel hatch cover for Ford F-550 and F-600 motorhomes?

Yes — The RV Fuel Vault is the first and only locking fuel hatch cover specifically engineered for Super C motorhomes built on Ford F-550 and F-600 chassis. Unlike universal gas cap covers or generic fuel hatches from auto parts stores, our fuel hatch cover is precision-built to fit the exposed dual diesel fuel cap configuration on these vehicles. Bolt-on installation in 8–15 minutes, no modifications required.

Does the RV Fuel Vault fit Ford E-450 Class C motorhomes?

Yes! The RV Fuel Vault now fits Class C motorhomes built on the Ford E-450 gas chassis. Compatible E-450 models include the Nexus RV Viper, Jayco Redhawk SE, Thor Four Winds & Chateau, Winnebago Minnie Winnie & Spirit, Coachmen Leprechaun, Forest River Forester LE, Phoenix USA Cruiser, and Coach House Platinum IV. If your Class C has an exposed fuel or gas cap, The RV Fuel Vault will protect it.

Does the RV Fuel Vault work with gas fuel caps or only diesel?

The RV Fuel Vault works with both diesel and gas fuel caps. It was originally designed for diesel fuel caps on Ford F-550/F-600 Super C chassis and has expanded to cover gas fuel caps on Ford E-450 Class C chassis. The product covers and locks over the exposed fuel cap area regardless of fuel type.

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Best Locking Fuel Door for Super C Motorhomes in 2026

10 min readMarch 2026

Why Super C Owners Need a Locking Fuel Door

If you own a Super C motorhome built on the Ford F-550 or F-600 chassis, you already know the problem: your diesel fuel caps are completely exposed on both sides of the vehicle. No factory door. No cover. No lock. Nothing between a thief’s siphon hose and your 50–80 gallons of diesel.

Every other class of motorhome — Class A, Class B, Class C — has some form of fuel door or enclosed fuel access. Super C motorhomes are the exception because they’re built on commercial truck chassis where exposed fuel caps are the standard configuration.

So what are your options? Let’s break down every locking fuel door and fuel cap security solution available for Super C motorhomes in 2026.

Option 1: Generic Locking Gas Caps

What they are: Aftermarket locking caps that thread onto your fuel filler neck, replacing the stock fuel cap with one that requires a key.

Brands: Stant, Gates, ACDelco, MotoRad

Price: $8–$25 each

The problem for Super C owners:

Most locking gas caps are designed for passenger cars and light trucks — not the commercial fuel filler necks on Ford F-550/F-600 chassis

Thread size often doesn’t match, leading to loose fits and check engine lights

Even when they fit, a determined thief can pry off a threaded cap in under 30 seconds with basic tools

You need two (one for each side), potentially with different keys

No protection against contamination from debris, weather, or road spray

Plastic construction won’t survive a serious attack

Verdict: Marginally better than nothing, but not engineered for Super C applications. A $15 band-aid on a $400,000 motorhome.

Option 2: Universal RV Fuel Tank Hatches

What they are: Multi-purpose access doors sold at RV parts stores. Typically a square or rectangular plastic door that mounts over a cutout in the RV’s body.

Brands: B&B Molders, JR Products, Ultra-Fab

Price: $15–$60 each

The problem for Super C owners:

Designed for travel trailers and Class C motorhomes where the fuel access is built into a flat exterior wall

Require cutting a hole in your motorhome’s body for installation — a major, irreversible modification

Made from thin UV-stabilized plastic, not security-grade material

Basic thumb locks or simple key locks offer minimal theft deterrence

Not designed for the specific fuel cap location and geometry on Ford F-550/F-600 chassis

Won’t fit over the existing fuel area without significant custom fabrication

Verdict: Wrong product for the application. Designed for different vehicles with different fuel access configurations.

Option 3: Chrome Fuel Doors (Truck Accessories)

What they are: Decorative chrome or stainless steel fuel doors designed for pickup trucks. Available from truck accessory retailers.

Brands: Various aftermarket truck accessories

Price: $30–$120 each

The problem for Super C owners:

Designed for pickup truck fuel doors — the recessed fuel pocket on the side of a truck bed

Completely wrong dimensions for Super C motorhome fuel cap locations

Most are cosmetic only — designed to look nice, not provide security

Even locking versions use basic push-button locks easily defeated with a screwdriver

Mounting system requires a specific recessed pocket that doesn’t exist on Super C motorhomes

Verdict: Cosmetic truck accessories with zero application to Super C motorhomes.

Option 4: DIY Solutions

What people try:

Welding a steel plate over the fuel area

Fabricating a custom lockbox

Using padlocks and chains

Epoxying the fuel cap and using a funnel to refuel

Price: $50–$500+ in materials and time

The problems:

Voiding your motorhome warranty with unauthorized modifications

Creating an unsafe refueling process (imagine fumbling with chains and padlocks at a busy diesel pump)

Poor aesthetics that hurt resale value

No engineering validation — potential to damage fuel system components

Difficulty accessing fuel caps for routine refueling

Verdict: Creative, but impractical and potentially dangerous. Not recommended.

Option 5: The RV Fuel Vault™

What it is: The first and only locking fuel door purpose-built specifically for Super C motorhomes on Ford F-550 and F-600 chassis. Patent Pending (Application 19/632,042).

Price: $149.95 per set of 2 (pre-order) | $199.95 retail

Why it’s different:

Purpose-built for the exact fuel cap location and geometry on Ford F-550/F-600 chassis

Heavy-duty steel construction — not plastic, not decorative chrome

Tamper-resistant keyed lock — not a twist-lock or push-button

Bolt-on installation using existing mounting points — no cutting, no drilling, no modifications

8–15 minute install with basic hand tools

Set of 2 covers both fuel caps (driver and passenger side)

Universal fit for all major Super C brands: Entegra, Jayco, Grand Design, Dynamax, Holiday Rambler, East to West RV, Fleetwood, Thor

24-month warranty and 30-day satisfaction guarantee

Made in the USA

What it protects against:

Fuel theft and siphoning

Contamination (water, sugar, sand, debris)

Vandalism and intentional tampering

Environmental damage (road dust, corrosion, weather)

Verdict: The only product on the market specifically designed, engineered, and manufactured for this exact application.

Comparison Table

Feature	Generic Locking Cap	RV Fuel Hatch	Chrome Fuel Door	DIY	The RV Fuel Vault
Designed for Super C	✘	✘	✘	Varies	✔
Ford F-550/F-600 fit	Poor	✘	✘	Varies	✔
Steel construction	✘	✘	Some	Varies	✔
Tamper-resistant lock	✘	Basic	Basic	Varies	✔
No modifications needed	✔	✘	✘	✘	✔
Blocks contamination	✘	Partial	✘	Varies	✔
Warranty included	Limited	Limited	Limited	✘	24 months
Made in USA	Varies	Varies	Varies	N/A	✔
Price (set of 2)	$16–$50	$30–$120	$60–$240	$50–$500+	$149.95

The Bottom Line

There is currently one product on the market purpose-built to solve the exposed fuel cap problem on Super C motorhomes: The RV Fuel Vault.

Every other option is either designed for a different vehicle, requires irreversible modifications, provides inadequate security, or some combination of all three.

For the price of a single tank of diesel, you can permanently secure both fuel caps on your $200,000–$500,000 motorhome with a product specifically engineered for your exact chassis.

Pre-order The RV Fuel Vault — $149.95 for a set of 2 →

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Ready to Protect Your Fuel System?

The RV Fuel Vault\u2122 \u2014 the first security fuel cap cover for Super C motorhomes.

Pre-Order Now \u2014 $149.95