Mazda has two types of coolant; regular and long life (FL22), I never had a chance to see FL22 but apprently both regular and FL22 are green, so color alone is not enough.
If you have the FL22 type coolant, you will have a sticker on the pressure cap saying FL22 can only be used, if you don't then it's a regular green coolant.
My mazda 3 manual has the following change intervals;
FL22 type*1 Replace at first 192,000 km (120,000 miles) or 10 years ;after that, every 96,000 km (60,000 miles) or 5 years
Others
Replace at first 96,000 km (60,000 miles) or 4 years ;after that, every 2 years