Ok now why should we use coolent.
1 - It will prevent water level to drop too early like normal water does.
2 - It will prevent your rubber pipes and water body ruber material to crack or give up early.
3 - it will help car to start better in cold weather and reach optimal temp.
4 - The most important the new engine have aluminium head and it can rust easily now when ever ur head gaskit blows or engine needs to rebuild if ur head is weak or rusted the mechanic will take the tool off the head it will be fine again lekin it add to the cost and after one or two tools it will be useless and the head will be more weak and car will also heat up early so use coolent to prevent rusting to head.
5 - It will help your radiator last long but radiator are not that expensive but engine head to me is much more important.
Now which coolent to use if you are going for normal go for green color DK coolent its made in japan and use atleast 3 bottles of it if u have never used it before. one bottle is for 80 to 100 Rs. Avoid osaka or anyother korean or taiwan brand
Caltex Coolent is also very good even better than DK.
The practice I do is ever month i not only change the oil filter fuel filter and air filter i also buy 1 bottle of DK and put it in my radiator.
Now i got a old car (Charade) and old car have prob of reducing water level but i hardly check my water level its always at normal level. MashaAllah