eli5 why do hydraulic storm door closers make a door so “heavy” on cold mornings?

Question

On warm days, the door will open easily. Why the sudden change when the temperatures go down?

In: Engineering

Answer 1

oil viscosity becomes higher at low temp and vice versa. this changes how easily the fluid can flow through the tiny channels to and from the spring side and reservoir side and therefore the apparent resistance of the cylinder from opening and closing motions.