Was chatting to a buddy and we got onto the subject of brake fluid (don't ask!) anyway, I asked what he had, dot 4, dot 5, or dot 5.1

He said he had "Castrol dot 5 synthetic brake fluid" I said 'dot 5.0???' as i've not seen it in in halfords (dirty word I know) I asked him about topping this up as I'd not seen it and he said that he was told he could mix his stuff with dot 4, 5, or 5.1, unless the stuff he purchased stated it could not/should not be mixed. I was a little concerned about this, so have a few questions.

1: Can you get dot 5 fluid? does castrol make it? if so what brand name is it and where would you get it from

2: can you mix and match fluids, and if so, which ones. I was under the impression that you should not mix the various grades.

3: what is the exact difference between the different grades?

4: is this guy off his trolley?

thanks

DOT 5.0 is incompatible with all the others IIRC (including 5.1 - it is completely difference - DOT 5.1 might be better being called DOT 6). The others can be mixed IIRC.

Try a google search and you can read about all the mysteries of DOT x.y and glycol/silicone bases and compatability. It is not very interesting.

brake fluid is the most common cause of brake fade (different to brain fade)as the
boiling point reduces as it takes in moisture.
silicone fluid works very well but in order to take thiis route if your car has been running on mineral fluid the system needs to be completely flushed as it will not mix.
the best way is to use a mineral based fluid if your car is notalready on silicone fluid
by using ebc bf307 which is the mineral based
fluid with a wet bioling point of 307 degrees c
this is available from SEJOC 01375 846401
at sensible money (dont forget to ask for scoobynet discount)