Don't you guys seriously remember Toady saying that he wants to keep DF's tech pre-1400? Oil makes absolutely no sense in the game anyway.
Also, the way I see it, the year 1 of the worldgen is just world 1 for civs, the rest of the world was happy and living.
While I definitely don't think Dwarf Fortress needs Polyethylene production and matching recycling plants, things like oil or gas
existed in the ground before the 1400s, so if you excavate large areas underground, you're going to hit them.
The reason why you took canaries into the coal mines is because those mines (even the ancient ones) had dangerous coal dust explosions, or pockets of gasses like methane that would explode from the flames of the torches and lanterns miners carried.
Things like natural gas, in fact, were and are used simply by transferring them by pipe and burning them. Dwarves have the technology to make pipes and to burn things, so burning natural gas pockets if and when we ever need lanterns or heating for personal homes by setting up pipes to pockets of gas would be perfectly reasonable for the technology that the dwarves already use.
Without going to search for when natural gas was first used for heating and lighting, I don't think it actually happened until the industrial revolution actually made humanity exploit coal deposits more heavily, but that's the thing - dwarves are already in the coal mines, and are already building their houses quite close to the sources of flammable gasses, so it should be technologically less of a leap for them.
Gasoline, meanwhile, I would think should be best relegated to the "Greek Fire" or "flamethrower" ideas, and definitely not the Internal Combustion Engine.