
In these contexts, yellow gas cans are scattered across the level (normal red gas cans can also be used if carried over from the preceding chapter to the finale, but their use to fill the generator in The Passing finale has been reported to cause game stability problems) and must be collected and carried back to a generator (or car) to refuel it. In Left 4 Dead 2, the new mode, Scavenge Mode, as well as the Dead Center and The Passing finales, uses gas cans as a non-offensive purpose. The most useful and generic tactic with gas cans is to spread them in an arc in front of a defended position, shoot at one can and to rely on its flames to ignite the unlit ones nearby, thus causing a large chain reaction and a wall of flame that helps with horde attacks and finales. Even on lower difficulties, where fire damage is usually negligible, the fact that all of the cans ignited together in the same spot means that all of the instances of fire are stacked in the same area, and that anyone standing in that area receives many times more damage from the fire than they would normally. This can spell disaster for a team because if cans are shot by mistake, the team will engulfed in flame and must flee its camping spot to become unexpectedly exposed and vulnerable.

On account of their efficacy when defending against large horde attacks and for survival maps, players will often attempt to stockpile them for later use.

Strangely, gas cans share the Molotov's glass shattering sound file when they are ignited. They are very effective when set up and ignited to create walls of flame providing a strong defense against large horde attacks. These cans are usually found around Crescendo Events and finales. There is no inventory space for this weapon, so the only method of transporting it is to pick it up and carry it. A player cannot shoot while holding a gas can but can still shove. They can be picked up with the Use key (default: "E" for PC "X" for Xbox 360) and release flames similar to a Molotov cocktail when shot.

The gas can, also known as fuel or petrol cans, can be found throughout the game.
