kam-325i wrote:Which engine is it.
It should have either a seperate expansion tank on top of the wheel arch, or it will be on the side of the radiator. Take the cap off and top up, But do it with a cold engine.
Carefull with advice like that, when we're dealing with someone who's car knowledge is as little as this.
I have a friend who once angrilly told his wife to top up the oil in her car after she reported the oil light comimg on around corners. She did that - right to the top of the cam box!!
Coolant should be added untill the level is up to the joint in the plastic, half way up the tank.
If your radiator cap doesn't have a yellow plastic disc on its bottom, take your VIN to the dealer, and ask for a new one.(Recall several years ago)