Skydrol is the hydraulic fluid used in airliners around the world and, I think, American fast jets. It’s a blue phosphate ester fluid, and by f*** does it burn when it comes in contact with mucus membrane. Be careful at the toilet...
Skydrol supposedly has fire resistant properties, but I think we are talking small differences over the red OM15 we used in the hydraulic systems on RAF fast jets.
I’m not sure why you’d use Skydrol as it would cause the OM15 type seals to swell, weaken and fail. Cross-contamination is a big no-no in workshops.