[Perfectlap]

Honestly, the expense of re-filling under pressure is worth the peace of mind.
You also want to make sure the tank is holding the minimum required pressure.
How old is the coolant? Is it all the same pink color?
if you mix cheap coolant with the pink Porsche coolant it will waste the protective additives.
Generally this is not an area where you want to take chances or guesses.

This is why getting a new cap is a good idea whenever you flush the coolant, replace the tank or just decide to test for leaks is a good idea.