Cold engine ... 89 BMW 325i

I cannot see a mark on the reservoir. How full should the reservoir be when the engine is cold? The car has not been driven in a few days.

I appreciate your help. I checked the online manual, but no mention of what level for the coolant.

Also, is there a specific coolant (brand/type) I should use? I live in southern Louisiana ... hot spring, summer, cool fall, and mild winters.

Thanks!