What is the best way to remove rust from the outside of a leaky radiator?

Question:I have a radiator that has leaked because the valve was previously not tightened up properly. It has leaked down the side of the rad and of course has left a rusty mark - how do i get this off?

I have tried whitespirit with noy joy

Please help.

Answers:
In order of preference
Brown sauce leave an hour wipe clean
Vinegar
If you have some try cylit bang ( I don't know the composition but it might work- tdon't but it specially)

Lime scale toilet cleaner
Car repair de-ruster ( gel type)

Brick cleaner that contains an acid ( phosphoric or hydrochloric , also called spirit of salts - look on the ingredients list)

BE CAREFUL WITH THE ACID PRODUCTS!
EYES , AND CARPETS COULD BE DAMAGED