Description
Tank Warden is our industry-leading, USA made, locking cap kit that protects your investment and prevents bystanders from contaminating your Diesel fuel and DEF systems, potentially saving you thousands of dollars in engine and emissions related repairs.
Each cap incorporates a highly manipulation resistant, quarter-turn lock cylinder that is prominently used in the casino industry. We opted to choose a lock that doesn’t use a wafer or tubular design, because those designs are insecure. Other locking caps require a cumbersome lock and unlock process and don’t utilize a real key and lock cylinder; why would you buy a ‘lock’ where everyone has the same key?
The caps incorporate an innovative design we developed and are incredibly easy to use. We even include an easy to use cap holder; no more messing with tethers! Unlike other locking caps that are tedious to use, you will find ours a joy to use.
Kit Contents
- Three keyed-alike keys. One for you, your spouse, and a spare!
- One locking green, laser engraved, Diesel fuel cap
- One locking blue, laser engraved, DEF cap
- One black cap holder
2011-2025 Ford Super Duty Diesel pickup trucks only. Not designed for cab and chassis trucks. Designed for trucks that have the OEM large, rectangular fuel door/pocket with the two OEM filler necks located within.
We cannot sell the Diesel cap by itself. Kits will include Diesel and DEF caps.
Each kit is keyed uniquely from other kits, and therefore multiple kits within the same order cannot be keyed alike for multiple trucks. For large fleets interested in identical locksets, please contact us here so we can discuss your requirements.
Ford and Super Duty are registered trademarks of the Ford Motor Company. Subtle Design has no affiliation with Ford or its partner companies.
Jeff Meyer (verified owner) –
Very nice high quality fuel caps. Convenient and easy to use and the supplied cap holder was well thought out!
Robert Siegel (verified owner) –
The quality of these caps is exceptional. Fit and finish are perfect, and the cap holder works well. Three keys are included. I wouldn’t hesitate to purchase these again.
wools64 (verified owner) –
So many thing you could say about this product. The main one anyone should know is that the design is excellent and well thought out and the quality is fantastic,its a top notch product. When mine arrrived I installed them right away, took less than 5 minutes. The press fit and locking design is excellent. You can take them off and on one handed as you fill up DEF or Diesel. One of my favorite features is the laser engraved lettering. Bottom line the Tank Warden cap holder is an excellent design, really impressed with the quality and the little things that were though out. (the install of the hanger, tool included, extra key, etc)
if you own a Ford Diesel Truck you know there are millions of aftermaket products you can buy for it. I suggest this product be right at the top of your list
DGW
Jarrod Leisch (verified owner) –
I installed mine yesterday and I am very impressed as well! I love the fact that it can be operated with one hand, removed with a 1/4 twist, and keeps the key captured. I had the BEM caps and always hated having to use both hands to unscrew the lock and remove the cap. These caps go on effortlessly and look fantastic. Job well done!
Vecman (verified owner) –
Well made, stylish, and easy to use. Would highly recommend this product to any truck owner. Huge upgrade from the stock caps that are just a pain to deal with. Another great Subtle Design product! Keep them coming!
TremorA31 (verified owner) –
Just installed mine. Superior design, perfect fit, rugged, and secure. The investment was well worth it. Highly recommend these for your truck. You won’t be disappointed.
Blumhagen (verified owner) –
This is hands down the best option for superduty locking fuel caps on the market. Install was a breeze.
RamblinHamblins (verified owner) –
Traveling full time in our RV we wanted to have the piece of mind having our tanks secured. We checked around and there were options, but none that really seemed good.
Thankfully this product showed up. It was worth the wait of development. We just received our shipment. Subtle Design reached out, knowing we were on the road, to find out where we were and where we could have the product shipped to us. They arrived the day before we got to the next town and were waiting for us when we got there.
Installation was a breeze and the build quality, fit and finish is great. The piece of mind of having our tanks secured is reassuring.
Great people to deal with and a great product.
https://youtu.be/vaBiYylT8kM
– RamblinHamblins
Michael Martinez (verified owner) –
Worth the wait, excellent quality and fit. Best fuel caps I’ve seen and highly recommend them.
Christiain Lee (verified owner) –
Exceeds OEM standards in quality, fit, and purpose. Easy to use and provides excellent security. Highly recommend!
Barry Downs (verified owner) –
Great product for piece of mind to know your fuel and def haven’t been tampered with. Very well thought out, simple install, and a high quality product.
Purchased 2 sets, and subtle designs reached out before shipping to verify that the quantity wasn’t a mistake. Excellent customer service!
Cole Hanly (verified owner) –
Great product, does exactly what is required without any extras.
Completely worth the wait, thanks again for putting out such a great product.
BoonesRide22 (verified owner) –
Fantastic product! Fit and finish are awesome. Great product to go on a great truck! The attention to detail top notch. Tank Warden, 3 keys, and holder all work flawlessly.
Thanks for putting such an awesome product out there.
John Oberto (verified owner) –
Awesome quality fuel and def caps . The security is second to none . I had the BEM caps previously for security/ safety, which is a very well made product, unfortunately there is only one key. When this series of locking caps were designed and put into production it was a a simple decision to upgrade the security of my fuel system. Also you could not ask for a better company to work with . 100% USA made and 100% plus customer service 👍🏻👍🏻
Stephen Stewart (verified owner) –
Excellent design of all three items. Well worth the price. Need to set up example truck on Ford dealer lot on Sundays. Keep up the excellent workmanship!
Ronald McClellan (verified owner) –
Just received my set and am completely satisfied with them. Easy to install, beautiful finish and easy to operate. Very happy to have that third key for “just in case” redundancy.
David Droegemueller (verified owner) –
Considering the complexity of designing, prototyping, testing, and ultimately producing a product like this, I can only say “very, very well done!” The quality, workmanship, and performance are superb. This adds another layer of confidence when I leave my truck at a trailhead. I won’t be at the mercy of bad actors with an unprotected fuel system! Everyone needs to get a Tank Warden if they run a Ford diesel like my 2022 Super Duty.
Glenn Lawton (verified owner) –
very happy with the appearance, functionality, and ease of use on my 2024 F250 … would recommend for all