Adds the specialized fluid "flamethrower fuel" (which can be barreled): equal parts light and heavy oil, based on the pre-0.17.6 recipe for flamethrower ammo.

At the default bonus setting of 1, gives a 35% damage bonus to flamethrower turrets (as opposed to 5% or 10% for heavy or light oil). Can be packaged in an assembling machine with 5 steel to create improved flamethrower ammo, which has a 33% damage increase over regular flamethrower ammo and splashes to a slightly larger area.