kosmo

How do we check it?

rnl

Wait until engine is cold.
Did I say, wait until it is cold?
open engine compartment.
on left hand side there are two caps. The coolant cap is on the left.

there is a float that will move from min to max.
it should be in the middle or around the middle of in and max.

I have topped off with distilled water and perma...something...having a senior moment just now.

Dr.Bill

Owner's manual, page 221.

TSpyder

I use Pentofrost mixed 50/50 with distilled water for topping off. I've had to top it off about 3 times in 6k mi after the red ball was at min. A buddy with 400 mi on a 6 mo old 991 just had an overheating episode b/c he neglected to keep an eye on the little red ball, and apparently missed a low coolant warning on the dash

Spyder

Hothonda

The red marker should be near the middle as in photo. Moisture on the oil cap
seems to be typical on these vehicles.