What dot?

[lambert]

It occurs to me that in the 2 and a half years i have had Bigbluemaverick i, being slack, have not changed the brake fluid. So is it worth going for 5.1 or to save a quid should i go for 4? Never had any fade as i'm not that heavy on the brake pedal, a bit of the last of the late breakers if you will, rather than riding them to smoke.

[Bulli]

dot 4 is ok, no point going for full synthetic unless you are racing it  

[marjan]

dot 4 is ok, no point going for full synthetic unless you are racing it  

And some of the older type seals don't like 5.1.

[Range Rover Blues]

dot 4 is ok, no point going for full synthetic unless you are racing it  

And some of the older type seals don't like 5.1.

I Didn't know that.

Is there any issure in mixing 5.1, say as you are bleeding out the old stuff?

I do have issues with my brakes, not big ones but they could be better.

[Bulli]

you wont get any benefit from 5.1 . its useful only in extreme use where you are getting temperature fade, it doesnt boil as easily.

and vehicles not designed for using it can have problems as Marjan said.

[V8MoneyPit]

Is there any issure in mixing 5.1, say as you are bleeding out the old stuff?

I do have issues with my brakes, not big ones but they could be better.

The manufacturers of brake seal kits we buy from specifically says not to use 5 with their seals. Also, we have seen seal failures with pattern cylinders when using DOT 5. And you can't always be sure with 'genuine' cylinders either. The likes of AP (Delphi) are buying in a lot of their cylinders from Italy these days so you get a nice AP box with a pattern cylinder inside... all for double the money!!

I believe you shouldn't mix 5 with older type fluids. But I might be wrong there.

I just stick with DOT 4 myself and have no problems. As said elsewhere, you shouldn't need higher temp fluid unless you are racing.