Winter storage and valve springs

Here is how I see it. Copied from an internet search.

The elastic deformation of a metal is a reversible occurrence where the metal can return to its original state. Metals that are deformed past the point where a return to their original state is impossible are referred to as being plastically deformed and not elastic. When stress or strain (tension or compression) is applied to a metal, a series of forces act on the metal forcing it to expand in an axial or radial formation - essentially elongating itself. If the applied stress or strain is within the force load allowances for the given metal based on its modulus of elasticity then the metal is said to be elastic and it will return to its original form when the forces are removed. If the applied stress or strain is greater that the modulus of elasticity determined range then the metal will be permanently deformed.

Just fog it for the rust factor.