TB993tt:

Re your 720S spider AC, my  720 Coupe did the same thing at about 16 months old I moaned to the service dept that my Porsche 997 manages to go many years without needing AC top up but he said the 720 used a much smaller amount of fluid, for weight saving, so would be prone to this "quirk".

I got the same explanation that it was only a tiny amount of fluid they needed to top up.