Crude Oil

Crude Oil is a dense mid-game liquid used as both a raw resource and a fuel precursor. It naturally appears in the Oil Biome, which lies above the Volcanic Biome near the bottom of the map, and it can also be extracted from an untapped Oil Reservoir by building an Oil Well over it and supplying water and power. In its natural, unpressurized state it stacks up to 870 kg/tile.

Several sources can produce Crude Oil. Slicksters excrete it after consuming Carbon Dioxide, Leaky Oil Fissures emit it directly, and rocket missions can harvest it from renewable space points of interest in Oily Asteroid Fields, where the renewal rate is 17–56.5 kg per cycle. The Oil Well converts water into Crude Oil at a rate of 1 kg/s water to 3.33333 kg/s Crude Oil. Because of this, sustainable oil production is ultimately tied to water input.

Crude Oil is most commonly refined into Petroleum. An Oil Refinery converts it at 50% efficiency and requires Duplicant labor, while heating Crude Oil to above 402.85 °C and below 541.85 °C converts it into Petroleum at 100% efficiency. This can be done with heat from magma or by warming oil from a Leaky Oil Fissure. However, if Crude Oil converts into Petroleum while still inside a pipe, the pipe still bursts, so pipe-based conversion is not safe. The liquid is also useful as a coolant: although it has only one quarter the heat capacity of Water, it has 4 times the thermal conductivity and a wide temperature range of 440 °C, making it a solid mid-game thermal medium.

Crude Oil also supports several power and recycling chains. Petroleum Generators burn refined petroleum, but their Carbon Dioxide output can be fed to Slicksters to recover some of that fuel loop. Molten Slicksters are more efficient for this purpose because they convert Carbon Dioxide directly into Petroleum, which can be burned again. That said, these loops remain dependent on setup quality and are not fully sustainable on their own without supporting infrastructure. Crude Oil can also be used in heating systems and preheating setups, especially when controlled with insulated cavities and temperature sensors.

A few practical notes matter when handling it:

• A Petroleum Generator can overheat its output. If the generator rises above 122.35 °C, its Polluted Water output flashes to Steam immediately, which can cause steam deletion in motion-heavy gas mixtures.
• For closed-loop petroleum systems, keeping generators below 120 °C and moving Polluted Water elsewhere for boiling or filtration is safer.
• Before the Automation Upgrade, Crude Oil could not freeze, which made it an especially effective cooling medium.

Crude Oil is therefore a key transition material: it is found in the deepest industrial layers of the map, can be produced from multiple renewable or semi-renewable sources, and serves as the foundation for Petroleum, heavy thermal management, and several late-game power schemes.