Fuel contains information about the BuildCraft mod.
Fuel is made by putting Oil through a Refinery. Fuel is used to Power combustion engines and can be stored in tanks or buckets. Refining Oil is worth it, as Fuel lasts 7.5 times longer in combustion engines than Oil. Fuel is the most efficent way of running a Combustion Engine , but keep in mind cooling the engine, or else the wonderful efficient Quarry setup that took you 5 hours to build will be no more!
While the Miner & Miner tested Fuel may look like your friend peed into the bucket you handed him to go refine some Oil, This is Chuck Norris approved, and will certainly explode your expensive Combustion Engine! Be sure you keep some water on hand at all times! (Not to let your friend drink then pee back out into the bucket.)