Please ref
https://bitcointalk.org/index.php?topic=1604125.0 dealing with liquid/immersion cooling a s9.
Mineral oil is NOT a good thing to use:
Only moderate heat-capacity (how well it absorbs/releases heat)
Viscosity highly variable with temp
Even when warm, is still not easy to pump
Attacks many plastics including Nylon (PCIe connectors), PCV (wire insulation) and elastomer (rubber) capacitor seals.
Much better choice are thermal transfer fluids designed for use with electronics and electrical parts such as
http://www.clearcoproducts.com/dielectric-silicone-fluids-sto-50.htmlWater-thin meaning easy to pump and flows very well around components, does NOT attack rubber/plastic, etc., very good thermal properties.
Silicone oil might not be a good idea for parts using silicone in them... Might be perfect for a transformer, but problematic for electronics.
Nobody will give you a certificate that all is well with his product.
This guys seem to know what they are doing:
https://www.grcooling.com/ and it is said to be mineral oil.