Looks like a visual glitch, but when putting shale oil in a large tank, it fills in from the top down, instead of the bottom up, defying gravity.

Pastebin with relevant mod info and screenshot showing the magical fluid called shale oil.

https://pastebin.com/r672cXuQ

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Not a visual glitch. Shale Oil was set as a gas in the code when it shouldn't be. An easy fix.