If you use your truck for work, trailer hauling, or for long trips in general, the need to carry extra fuel has likely presented itself. We're not talking about stashing a spare gallon in the bed to save your skin in an emergency. Many truck owners need to carry 40, 50, or maybe even 100 gallons of extra fuel for various reasons.
If you're considering joining this group, you've likely done some research on how exactly you could efficiently (and safely) carry that much extra fuel. Along the way, you’ve come across auxiliary fuel tanks and liquid transfer tanks. While they may seem similar at first glance, they actually serve pretty distinct purposes.
Understanding the differences between auxiliary and transfer tanks is important before you make a purchase. Otherwise, you might find yourself with the wrong tool for the job. We're here to provide clarity, so you can get the most out of that spare fuel you plan to carry.
What is an Auxiliary Fuel Tank?
Let's start with auxiliary tanks, as these are what most people think of when they set out to equip their trucks for extra fuel storage. The best way to think of auxiliary tanks is as an extension of the existing fuel system.
Simply put, they increase fuel capacity and extend the range of your vehicle. This means you can drive further and longer without having to stop and fuel up as often.
This can save a lot of time and trouble if you're hauling a trailer over long distances. It can even save you money on fuel costs, as you can fill the system completely where fuel is the cheapest.
What Should I Know about Auxiliary Fuel Tanks?
Designed to permanently mount in the truck bed, auxiliary tanks are plumbed into the vehicle's fueling system. This is an important feature to consider, as some modification made during installation cannot be undone without replacing altered fuel system components.
It's also worth noting that installing an auxiliary tank requires drilling holes in the bed to allow the fuel lines to feed to the factory tank.
While these tanks can be used for both gasoline and diesel applications, there are critical legal differences that come into play when tapping into the truck's existing fuel system. For example, gravity feeding is perfectly legal for diesel trucks, but not gasoline.
Gasoline systems must pull fuel from the top with an inline pump that can be operated automatically or manually to refill the factory tank. That said, you will want to check with local regulations to ensure proper setup of either system.
If you're hesitant to sacrifice precious bed space in your work truck for a large external fuel tank, there are other solutions to explore. For example, RDS, a leader in this space, offers both auxiliary tanks and replacement fuel tanks for select makes and models.
The replacement fuel tanks bolt right in place of the factory fuel tank, and can double storage capacity. They're also built with high-grade aluminum, which offers superior durability compared to the plastic tanks found in many of today's trucks. This is a step worth considering before permanently dedicating bed space to an auxiliary tank.
So, What’s a Liquid Transfer Tank?
Similar to an auxiliary tank, a liquid transfer tank mounts to the bed of your truck. However, its intended purpose is different—it's not designed to add capacity your existing fuel system.
Instead, a transfer tank essentially transforms your truck into a refilling station. Equipped with an external pump like those found at gas stations, it enables you to refuel multiple vehicles, including your own.
This kind of versatility is great for anyone who frequently operates multiple vehicles or machinery, especially at remote job sites or during long trips. Additionally, for businesses or work truck operators who need to refuel other equipment on the go, like generators or lawnmowers, a liquid transfer tank is a convenient and cost-effective fuel solution.
What Should I Know about Liquid Transfer Tanks?
As mentioned, liquid transfer tanks operate via external pump. While you can use them to refuel the truck carrying them, it won’t be an automatic process. This is because transfer tanks are not integrated into the vehicle's fuel system like an auxiliary tank.
Consequently, this makes transfer tanks a less permanent fuel storage addition. Yes, you’ll need to drill holes to mount it to the truck bed but, ultimately, these are standalone units that can be removed or transferred between vehicles.
Another feature of liquid transfer tanks is that they can carry a variety of different liquids, including water or chemicals. For example, agricultural companies might transport water for irrigation system refilling or liquid fertilizers to apply to crops and lawns. So, if you’re planning to use one for fuel, make sure it’s DOT-approved for the fuel type you intend to carry in it.
RDS, DeeZee, Weather Guard, and TrailFX all offer high-quality liquid transfer tanks worth considering. RDS even has a model that can carry two different liquids at once, so you can tote different fuels for different vehicles you may be working with.
Which is Better for When?
Determining whether an auxiliary fuel tank or a liquid transfer tank is better for you depends on your specific truck usage and the reasons for needing extra fuel or liquids.
If you frequently find yourself driving long distances or hauling heavy loads and need to extend your vehicle's range, then an auxiliary fuel tank might be the way to go. On the other hand, if you often need to refuel multiple vehicles or equipment on the go, a liquid transfer tank could be more suitable.
Either way, the next step in the process is selecting the right shape and size tank to meet your needs.
Both auxiliary and transfer tanks come in various capacities and shapes to accommodate different applications. For example, L-shaped tanks are popular work truck fuel solutions because they allow space in the truck bed for a saddle tool box. Some tank styles even come with built-in toolboxes for added convenience.
Keep in mind, however, that these are just general guidelines – and there are always exceptions to the rule. For instance, some auxiliary tanks can be equipped with external pumps, allowing them to serve both as additional, integrated fuel storage and as refilling stations.
Ultimately, finding the right solution involves asking the right questions and doing thorough research, because there really is a solution for every demand. With the information provided here, you're better equipped to navigate the options available and find the tank that best fits your needs.
We recommend starting with some of the top brands in the segment, including Dee Zee, RDS Tanks, Titan Fuel Tanks, Transfer Flow, UWS, and Weather Guard – all of which are available right here on Parts Via. Plus, keep in mind that these big and bulky purchases are great candidates for Parts Via’s ship-to-store program, which allows you to ship your auxiliary or transfer tank straight to a registered network dealer, free of charge!