Power Steering

I've been having some issues with the power steering in my 1991 SC.

It works fine, except that it seems to slowly leak out and needs to be refilled every 2-4 weeks.

When I added some ATF yesterday, I realized that the fluid (in the power steering fluid reservoir) was a weird gray color.

What are some things that could cause the power steering fluid to turn gray, and how urgently should it get changed?

Sounds contaminated - either from internal component/hose failure~deterioration and/or something introduced that doesn't belong, such as water, etc.

I'd try to replace as much as practical, being careful to bleed properly and being patient when topping off... and not turning the wheel too much with the engine off/wheels in the air. Look for fluid wetness on the lower IC right below the front of the pump...this can indicate a leaking seal and/or failing pump. I've had success just replacing the front seal without removing the pump, but if it's more serious, I would simply get a new/rebuilt pump and be done...hoses too if suspect.

Be careful to not overfill and be sure to use the right fluid.