I Tested the 2022 Ford Diesel Royal Truck Body Locking Fuel Caps: My Honest Review and Buying Notes

This model earned its top spot through dual-port protection, securing both your main diesel fuel and your DEF reservoir in one package. I rank this as the best overall choice because modern Super Duty owners need a unified security solution rather than piecemeal parts.

The build quality uses heavy-duty materials designed to resist tampering and weather degradation. You will appreciate the straightforward installation that does not require special tools. My primary reservation is that the fitment is strictly narrow, meaning it will not accommodate older truck generations.

Drivers of older generation heavy-duty trucks will find this tailored security option fits their specific filler neck geometry. I consider this a smart investment if you drive a 2017 model and want peace of mind against fuel contamination.

The locking mechanism operates smoothly even after exposure to road salt and grit. You get a reliable seal that prevents vapor leaks while keeping unauthorized hands away. My only hesitation is that the included keys can feel a bit lightweight compared to industrial padlock standards.

The inclusion of a factory green color code immediately signals this cap belongs on a modern diesel application. I view this OEM replacement as the safest route if you simply want to restore original factory specifications without aftermarket locks.

The tether keeps the cap attached securely during fill-ups so you never leave it sitting on a pump island. You receive genuine Ford engineering that guarantees a proper pressure seal and zero check-engine lights. My critique is that it lacks any physical lock, leaving your fuel completely exposed to siphoning.

The most common complaint from buyers centers on how tricky it is to secure modern capless fuel systems. I think this adapter-style lock provides a clever workaround for a notoriously difficult design.

The unit inserts directly into the factory opening to block unwanted access while maintaining the standard fueling process. You gain a physical barrier against outside elements and tampering. My reservation is that the extra mechanism can sometimes feel bulky when you are trying to insert a heavy diesel nozzle.

Compared to the narrow specialization of my top pick, this option targets a much wider range of older Ford trucks and vans. I find this versatility appealing if you manage a mixed fleet of older work vehicles.

The universal locking core uses a dependable turn-to-release mechanism that most drivers already understand. You benefit from a wide distribution network that makes replacements easy to source. My concern is that older universal designs often lack the advanced weather sealing found on modern truck-specific variants.

This cap earned its market reputation through a simple budget-friendly approach to basic fuel safety. I see it as a decent entry point if you need basic security without spending a premium.

The heavy-duty plastic construction withstands daily use without cracking under normal pressure. You get a dependable lock tumbler that keeps casual thieves at bay. My hesitation stems from reports that the internal gasket can degrade faster than OEM materials over time.