Petroleum

Petroleum is a mid-game liquid element with a wide usable temperature range and relatively high thermal conductivity, making it a strong coolant before more advanced options become available. It has a much lower heat capacity than Water, but its conductivity is four times higher, so it can move heat efficiently while remaining stable across a broad range of temperatures.

It is primarily obtained by refining Crude Oil in an Oil Refinery, which converts 10 kg/s of Crude Oil into 5 kg/s Petroleum and 90 g/s Natural Gas at 50% efficiency. Crude Oil can also be heated above 402.85 °C and below 541.85 °C to convert it directly into Petroleum at 100% efficiency. In overheated map regions, Petroleum may also appear naturally when Crude Oil transforms, and Molten Slicksters can produce it as part of their lifecycle.

Petroleum has several important industrial uses throughout the late mid-game and into the endgame:

• Polymer Press uses Petroleum as a raw material to produce Plastic.
• Petroleum Generator burns it for power, producing Carbon Dioxide and Polluted Water.
• Petroleum Engine uses it as rocket fuel, with the fuel stored in a Liquid Fuel Tank.
• Blastshot Maker consumes Petroleum to craft Blastshot.
• Exosuit Forge uses Petroleum to produce Jet Suits, and Jet Suit Docks use Petroleum to refill the suits’ jetpacks.
• Molecular Forge consumes Petroleum to produce both Visco-Gel Fluid and Super Coolant.

For Molecular Forge recipes, Petroleum is combined with Isosap to make Visco-Gel Fluid, and with Fullerene, Gold, and additional Petroleum to make Super Coolant. Petroleum is also one of the materials used in Jet Suit production, along with Steel.

Petroleum can also be deliberately broken down through temperature control. Heating it to 541.85 °C turns it into Sour Gas, and cooling that Sour Gas to -164.5 °C converts it into Liquid Methane and Sulfur. Liquid Methane then boils back into Natural Gas at -158.5 °C. This chain is useful for advanced gas processing and resource conversion, especially when managing extreme heat or trying to extract additional fuel products from crude hydrocarbon streams.

Because of its combination of broad temperature tolerance, useful industrial applications, and relatively good thermal transport, Petroleum is one of the most versatile liquids in the game. It is especially valuable as a coolant where Water is no longer ideal, and as a bridge resource for Plastic, jet suits, rockets, and late-game manufacturing.