Own a Dynamax Isata?
“Lock Your Fuel Doors.”
The RV Fuel Vault is the only purpose-built locking fuel door for RVs — engineered to fit Dynamax motorhomes like the Isata 5 Super C on the Ram 5500 chassis and the Isata 3 Class C on the Mercedes Sprinter.
Use code DYNAMAX and save $10 per door
Why Dynamax Isata Owners Swear By It
Your Isata is a serious investment — but that exposed diesel fuel cap and blue DEF cap on the chassis are left wide open. The RV Fuel Vault is the simple upgrade that finally puts that worry to rest.
Diesel Theft Protection
A tamper-resistant keyed lock stops siphoning and vandalism. No more worrying about your diesel at campgrounds, truck stops, or storage.
DEF Contamination Defense
Seals your filler neck and DEF cap against water, road grime, and cross-fills that can total an emissions system ($8k–$20k+ in repairs).
Factory-Finished Look
Replaces the ugly exposed green diesel cap and blue DEF cap with a clean, armored finish worthy of your Isata. The part the factory forgot.
8–15 Minute Install
No drilling, no cutting, no body mods. Bolts on over your existing filler neck with basic hand tools.
Lifetime Warranty
High-strength UV-resistant polymer built to last. Backed by a Limited Lifetime Warranty. Made in the USA.
Free Shipping
Free standard shipping on every order. One key opens the diesel door, passenger-side door, and DEF cover.
See the Difference
This is what the Isata rolls off the lot with: an exposed, unprotected fuel cap. The RV Fuel Vault changes that.
❌ Before — Exposed & Vulnerable
✅ After — Locked & Protected
Built for Your Isata — and Every RV You Own
Engineered for Dynamax motorhomes like the Isata 5 Super C on the Ram 5500 and the Isata 3 Class C on the Mercedes Sprinter, the RV Fuel Vault also fits every other major RV type. Use the fitment finder to confirm your exact model.
Super C Motorhomes
Dynamax Isata 5 on Ram 5500 & more
Class C Motorhomes
Dynamax Isata 3 on Sprinter, Ford E-450 & more
Class A Motorhomes
Ford F53, Workhorse chassis & more
Class B Campervans
Ram ProMaster, Mercedes Sprinter & more
Toy Haulers
Fuel cap protection for your hauler
Fifth Wheels & Trailers
Protect the truck that tows your rig
Dynamax Isata Discount: $10 Off Per Door
Use code DYNAMAX at checkout — or just order through this page and it's applied automatically.
Free shipping • 30-day satisfaction guarantee • Limited Lifetime Warranty
From one RV owner to another:
“I added these to my own rig and honestly wish they came standard. That exposed fuel cap always bugged me — it's a security risk, a contamination risk, and it looks unfinished. The RV Fuel Vault fixed all three in about ten minutes. If you camp, travel, or store your RV like I do, do yourself a favor and get one.”
— A fellow RV owner & RV Fuel Vault partner