There is no chance 1996 121 engine will work efficiently with bad cooling. Don’t underestimate the importance of Mazda’s 1.3 engine cooling system. For sufficient use of Mazda 121 you need to use suitable antifreeze. Before choosing fluid note that engine code DHG and volume of 1.2 were installed to your car in 1996. To maintain cooling system you need 7.6 liters of Red coolant.
It’s obvious that every DHG motor needs good service as stated by Mazda in instruction. 1.2 121 motors of 1997 year will serve more by optimal service. Look at Mazda’s requirements and make your 1993 121 serve longer and with no problem. To endure car life take only Red antifreeze and pour not more or less than 7.6 liters.