Galacticraft oil generates between y-levels 20 and 30 in small pockets.
Oil can be extracted using a {Portable Oil Extractor}. Once extracted oil can be refined into rocket fuel in the refinery.
Oil from other mods can be used in the refinery, using buckets or by piping it into the sides.
Oil generation can be disabled in the config, but if you don't have another mod that adds oil you will not be able to produce fuel.
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