Yes you can put coolant right into the radiator. Just make sure it is a 50/50 mix of the correct anti-freeze and distilled water.
Never put just straight water in your motor. You want to top off your radiator first then top off your coolant in the reservoir. Water will rust your motor from the inside out.
In the radiator
With the engine cold, put it in the radiator just to be sure there is no air gap. Run it for a short time until it gets warm and coolant begins to circulate. Then install the radiator cap and put coolant in the overflow to the coolant level line.
The coolant goes into the reservoir only that says coolant. You don't put it in the radiator.
Radiator. Remove the cap and add coolant there.
In the radiator
Pour the coolant in the radiator.
Coolant for a 2006 VW Bettle is put into the coolant overflow tank. As it is needed, the radiator will automatically pull in additional coolant.
Under the hood on the left side in most cases there is a place to put in radiator coolant.. It is usually next to the windshield wiper fluid... It says radiator coolant on it
Take radiator cap off, fill radiator with coolant, put cap back on!
The Fiat Punto has a radiator which receives coolant in order to keep the temperature down. The diagram of this radiator can be found in the owner's manual.
Add the coolant into the coolant reservoir. Be sure the engine is cool when you remove the cap off the reservoir.