Gas can

Gas cans, also known as fuel or petrol cans; can be found throughout the game. 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. A player can not shoot while holding a gas can, but can still melee. There is no inventory space for this weapon, so the only method of transporting it is to pick it up and carry it. These cans are usually found around crescendo events and the finale. They are used to set up traps and provide a strong defense during large Horde attacks.

Tactics

 * The gas tank has a wider area of effect than the molotov cocktail, making it more effective for large choke points and wide open spaces.


 * If placed before a showdown or event, the gas tank can be significantly less dangerous than thrown weapons. Due to lag or confusion, a molotov cocktail and pipe bomb can land in close proximity to the survivors, making them a detriment and sometimes forcing the survivors to abandon their preferred choke point.  The gas can provides a safe weapon that can be set of from a distance with no risk of accidental targeting.


 * The gas tank can be carried from level to level if it is brought into the safe room. If you find a gas tank near the end of the level, it might be more valuable to save it for the next level than waste it (Campaign and single player only, not versus).


 * While it is often better to drop the gas can for hordes, small groups and single common infected can be killed with the melee attack of the gas tank. This means it can often be carried much further than most people think.


 * Fire doesnt normally burn in water and but has been known to burn in a few bodies of water.

Survivor Tactics
Usually in the finale's of levels you will find some Propane tanks and Gas Cans, Its best to drop them in choke points where you know the zombies will come then detonate it with a Hunting Rifle Shot,Beware of the area of effect it spreads to though dont get caught in it. It is also very effective against tanks place the Gas Tank wait for the tank to get near it and shoot the tank, Setting the tank on fire for a sure kill. A well placed gas tank can mean life or death on finale's on Advanced/Expert

Infected Tactics

 * Gas cans, in addition to propane tanks and oxygen tanks, give a clear signal of where the survivors expect infected to come from. you can use this to your advantage by spawning or moving to areas that are in opposite directions of these weapons.