The amount of fuel required to fill an 18-wheeler or semi-truck can vary depending on a number of factors, including the size and fuel efficiency of the truck, the distance being traveled, and the type of fuel being used. In general, however, most semi-trucks have a fuel tank capacity of between 100 and 300 gallons.

Assuming a typical semi-truck has a fuel tank capacity of 200 gallons, it would take 200 gallons of fuel to fill the tank from empty. This is equivalent to approximately 757 liters, or 53.3 barrels of crude oil, as a gallon of diesel fuel is produced from roughly 0.27 barrels of crude oil.
The cost of filling an 18-wheeler’s fuel tank will depend on the current price of diesel fuel, which can vary widely depending on location and market conditions. As of March 2023, the average price of diesel fuel in the United States is around $3.75 per gallon, which would make the cost of filling a 200-gallon fuel tank around $750.
It’s worth noting that the fuel efficiency of a semi-truck can vary widely depending on factors such as the size and weight of the truck, the terrain being traveled, and the driving habits of the operator. In general, however, most semi-trucks get between 6 and 8 miles per gallon (mpg) of diesel fuel. This means that a semi-truck with a 200-gallon fuel tank could travel between 1,200 and 1,600 miles on a single tank of fuel, assuming an average fuel efficiency of 7 mpg.
In summary, it can take between 100 and 300 gallons of diesel fuel to fill the tank of an 18-wheeler or semi-truck, depending on the size of the tank. Assuming a fuel tank capacity of 200 gallons, it would take 200 gallons of fuel to fill the tank, which could cost around $750 based on the current average price of diesel fuel in the United States. However, the actual cost and fuel efficiency of a semi-truck can vary widely depending on a number of factors, and it’s important for trucking companies and drivers to carefully monitor fuel consumption and costs to maximize efficiency and profitability.