Sorry, I did some research, it's not just hydraulics, but at below -30 materials experience significant changes in strength and many become brittle and prone to breaking, demanding that they be shut down.
My mechanic father has a saying - badly maintained stuff breaks down at -30 C, but everything can break at -40 C.
Well, then you'd better choose materials that are appropriate for the location. There are wind turbines in Antarctica. It's just a matter of engineering.
My mechanic father has a saying - badly maintained stuff breaks down at -30 C, but everything can break at -40 C.