Change coolant every two years or every 20, 000 kilometers.
First remove top coolant cap
Then remove radiator bottom plastic drain bolt. Its positioned in front of the car.
4 Liters of coolant is required.
You can take 3 liters of distilled water and 1 liter of coolant.
Bad coolant will cause rust inside the radiator.
Use geniune coolant.
Remove reservoir, drain it completely and clean it properly.
Fill from top. when completely filled, start the engine. Level will go down. bubbles will come. Keep engine running till no more level drop. Then fill again.