Golf Mk2 - correct coolant mixture ratio - golf-driver

I have a Mk2 Golf 1300.

What is the correct antifreeze ( G12 ) / water ratio to prevent corrosion in the coolant system?

Will 30% / 70% be alright? Where I live the lowest possible winter frost is only -5 C so I don't need 50 / 50

Golf Mk2 - correct coolant mixture ratio - unthrottled

Absolutely fine. Still not sorted your cooling woes out?!

Golf Mk2 - correct coolant mixture ratio - golf-driver

I have replaced the leaking radiator.

The leaking radiator only lasted for 28 k