oil footstep 1-4 extracted from https://freesound.org/people/VlatkoBlazek/sounds/318592/
Released under the CC BY 3.0 license by:
Vlatko Blažek
Varaždin, Croatia
e-mail: vlatkoblazek@gmail.com
http://www.freesound.org/people/VlatkoBlazek/

oil_gas_seep_hiss.1 is from https://freesound.org/people/wubitog/sounds/234782/ under the public domain (CC0)
oil_gas_seep_hiss.2 is from https://freesound.org/people/kgatto/sounds/240263/ by kgatto under the CC-BY-3.0 license