How much antifreeze for a Mazda mx5 1.6?

Depends on your climate conditions. Assuming that the conditions don't get much lower than -15deg celsius, then 33 percent antifreeze should be adequate. purchase 2litres of antifreeze and pour into 4litres of water, drain and refill radiator - BUT LET THE ENGINE TICK OVER WITH THE RADIATOR CAP OFF for a while to get rid of airlocks. Six litres should be adequate for most cooling systems, but if you have serious cold, then 50 percent would be advisable.