Premixed Antifreeze brand?

[DaveNW]

I was out driving today, and after a few hours, the coolant light came on intermittently. When I got home and the engine cooled down, I checked, and see the fluid level needs to be topped up. In the Owner's Manual it says to only use "Porsche approved" products. Is that a certain brand or type, or is something off the shelf like Prestone Premixed good enough? Is there something better I should use?

Thanks,
Dave