Can anybody tell me if I can replace my standard brake fluid with the Dot 5.1 type and is there any advantage? Does it need replacing every 2 years like the standard stuff as I understood it doesn't absorb water the same way.

You can, but personally id go for super dot4.

Any particular reason?

The dealer on my country, Colombia, puts DOT 5.1

And replaces it every 2 years or 20k km (the cars are set to 10k km fixed service intervals).

Any particular reason?

Yes. The dry boiling point is only just below that of 5.1 and in some cases the wet is actually higher. It is also compatible with your existing fluid so if you haven't completely flushed the system, no harm done. It also keeps the standard flud change intervals whereas the 5.1 needs changing more often

Thanks for the info. Think I'll try and get some Castrol Response 4.1+.

Anybody know how much brake fluid I'd need to replace it all?

Autodata CD2 gives the capacity of the brake system as 0.6 litres of DOT4. I guess you will need more than that to flush all the old fluid out.

I bought 2 litres so should be covered.