Which break fluid for Citroen C4

[quazar]

I need to top up break fluid on my 2007 Citroen C4 2lt Unleaded.
Which type of break fluid I should use. I noticed there are DOT4, DOT5.1 etc stuff but I am not sure which one to go with. Your help much appreciated.

Regards

[addo]

If the level of fluid is low you should first investigate why. Perhaps your brake pads need replacing.

DOT4 would be correct, however DOT5.1 will also suffice. Please note that 5.0 is very different to 5.1 and not compatible.

[quazar]

Thanks very much. I know the reason because a guy replaced the O2 sensor at the back and he made the container upside down. After that I have noticed the fluid level in deep.

[Monkeyfeet]

Are you saying that the whole car was titled to replace the sensor, is this normal on C4s? If you think fluid escaped from there reservoir can you see any spillage at all?
Agree with addo, get DOT4 if poss.

[Chlorate]

DOT 4 and 5.1 are practically the same stuff and can be mixed, the only difference is that 5.1 has a higher boiling point than 4.

Unless you're regularly boiling your brake fluid DOT 4 is fine