How Do Dual Fuel Tanks Work on Semi Trucks?

Dual fuel tanks are a vital component of semi-trucks, providing the ability to run on two different fuel types, which is advantageous in various scenarios. Dual fuel tanks contain two separate compartments, each capable of holding a different fuel type. This feature lets the truck driver switch between the two fuel types depending on availability or need.


Dual Fuel Tank Configurations 

There are several ways to set up dual fuel tanks, the most common being to have one tank for diesel fuel and another for gasoline. This configuration permits drivers to switch between the two fuel types based on availability or need. Another general approach is to have one propane tank and another gasoline tank, providing similar switching capabilities.

Importance of Dual Fuel Tanks for Semi-Trucks 

Semi-trucks differ from other trucks because they are larger, have a special trailer attached to the back for carrying large loads of goods or materials, and are typically used for long-distance travel. Thus, dual fuel tanks are essential as they allow drivers to switch between the two fuel types depending on availability or need.

Semi-Truck Length and Carrying Capacity 

A semi-truck typically measures about 40 feet long, with an attached trailer adding 20 feet. The truck can carry a maximum weight of 80,000 pounds (40 tons), depending on the truck and the trailer.

Difference Between Semi-Trucks and Tanker Trucks 

Tanker trucks are designed to transport liquids or gases, featuring a single large tank to hold the substances. These trucks transport gasoline, oil, and milk, among others. On the other hand, semi-trucks are designed to transport solid goods using a large trailer attached to the back. These goods include furniture, boxes, and cars.

Dual Fuel Tank on Semi-Trucks FAQs 

Not all semi-trucks have dual fuel tanks; those that do not may only have one tank filled with diesel fuel. Although filling both tanks is not mandatory, it is advisable to maintain a full tank of each fuel type for flexibility. Dual fuel tanks are not required, but they offer immense benefits such as accessibility to an alternative fuel type, cost savings when one fuel type is expensive, and quality fuel access in lower-quality regions.

Filling Dual Fuel Tanks 

Filling dual fuel tanks is similar to filling a single tank but requires a few extra steps. Determine the fuel type required, locate the appropriate pump, and proceed to fill the tank. Never mix different fuel types in the same tank, as it can cause engine damage and other problems. It is best to seek professional guidance if you need clarification on the fuel type.

Semi-Truck Fuel Tank Capacity 

The fuel tank size determines the amount of fuel a semi-truck can hold. Most semi-trucks have tanks ranging between 100 and 200 gallons, sufficient for extended operation.

Semi-Truck Fuel Efficiency 

Semi-truck fuel efficiency varies depending on the tank size. However, most semi-trucks can travel between 500 and 1000 miles on a full tank. This is advantageous for long-distance travel, the primary use of semi-trucks.


Dual fuel tanks are a valuable component of semi-trucks, allowing drivers to switch between different fuel types. Dual fuel tanks are not mandatory but offer several benefits, such as flexibility, cost savings, and quality fuel access. Understanding the use of dual fuel tanks, including filling and capacity, is vital for truck drivers to be prepared for any eventuality.

About the author, Laurence Perkins

Laurence Perkins is the passionate car enthusiast behind the blog My Auto Machine. With over a decade of experience in the automotive industry, Perkins has knowledge and experience with a wide range of car makes and models. His particular interests lie in performance and modification, and his blog covers these topics in-depth. In addition to his own blog, Perkins is a respected voice in the automotive community and writes for various automotive publications. His insights and opinions on cars are highly sought-after.