I had the idea of throwing oil flasks on enemies at level 1, then hitting them with a torch to deal a bunch of bonus fire damage.
PHB 152:
If the target takes any fire damage before the oil dries (after 1 minute), the target takes an additional 5 fire damage from the burning oil.
PHB 152:
If you make a melee attack with a burning torch and hit, it deals 1 fire damage.
A flat 6 fire damage is pretty potent at level 1, but does the oil remain or does it burn out in a flash when hit (since it has no damage over time) when hit?
If not there is potential for a dual torch wielding PC to throw down 12 fire damage per round, or for multiple PCs to deal 6 damage per torch per PC per round.
Best Answer
Yes, it is consumed.
In the PHB 152 it is described what happens when a part of the floor is drenched with oil and lit (emphasis mine).
What it is not told is what happens with the oil on the creature. Logically one may say that the oil would burn for 2 rounds mimicking the mentioned effect. But there are plenty of evidence that fire does not stay in creatures unless specified. For example; Burning hands, Fireball, Delayed Fireball, and Meteor Swarm are spells that clearly specify that no worn objects catch fires, and one of these is a level 9 spell; a mere oil would not light a candle to that. Furthermore, the text ends with a full stop where it should state something in the lines of "every round for two rounds", or so.
It is important to emphasis that flammable is also a description of oil.