Your Mini Cooper needs antifreeze, also known as coolant, to prevent your engine from freezing during the winter. It also prevents your engine from overheating. The type of coolant you should use for your Mini Cooper is a 50/50 mixture, 50 percent antifreeze and 50 percent water. If your antifreeze is more than 3 years old, discard the old coolant and purchase a fresh container.
Allow 10 to 15 minutes for the engine to cool down. You can tell whether the engine is hot by looking at the temperature gauge on the instrument panel. Smoke coming from the engine is another indicator that the engine is hot.
Open the bonnet (hood) of your Mini Cooper. The first release lever for your bonnet is underneath the instrument panel on the passenger side. Pull the first release lever to pop the bonnet. Reach underneath the bonnet and pull the second release lever back to fully open it.
Locate the coolant tank. Instead of being located on the front, near the radiator, the tank is actually at the back center of the engine.
Slowly remove the coolant tank cap. By removing the cap slowly, you are allowing the built-up pressure to escape. If the coolant tank has a "Cooper S," the cap will unscrew. Otherwise, the cap can be pulled off.
Pour the coolant slowly into the coolant tank. Fill the tank until the fluid level reaches the "Max" marking. This mark indicates the maximum amount of fluid that should be added. There is also "MIN" marking indicating the minimum amount of coolant that should always be in the tank.
Replace the cap for the coolant tank and tighten securely. Close the bonnet.