Brake fluid spec please

[Cherrypd]

I need to top up my brake fluid (only a little), but if I don't the world will spin the other way. Handbook says consult your MD for the specs. So I can look at other outlets, whats the spec I should be looking for?.

E250 CDI, 2010.

 

[Trickythemerc]

Dot 4/5

 

[rf065]

Don't use Dot 5, it brings about it's own problems, especially if your already using Dot 4.

 

[Trickythemerc]

Typo in post should have been DOT 4/5.1 DOT 5 is silicone based and will not mix with glycol based fluids.

 

[Smiley]

Don't overfill the master cylinder; the fluid level drops as the pads wear. If it is dropping more than that then the source of the leak needs to be found asap. The most likely source of the leak is from a rusted rear brake pipe.

 

[190]

The correct spec for your brake fluid is a low viscosity dot 4. It will be marketed as Dot 4 LV, Dot 4 super, DOT 4 plus and there are others. They are all thinner versions of Dot 4 with a maximum viscosity of 750 cSt @ -40 Deg C. compared with 1800 cSt@ -40 Deg C for normal Dot 4. They are intended for use in modern brake systems with ABS etc to speed up response times of the electronic brake functions in cold weather.

The reason for the various names is that there isn't yet or perhaps ever going to be an official Dot standard for low viscosity Dot 4 brake fluid so they are all just marketing terms. It’s very confusing that each manufacture thought it appropriate to invent their own name. There is though one common term to look for in the small print. Often you’ll see them marketed as DOT 4 + class 6 (or any of the other variations followed by class 6) which is a clue to what they really should be called. This refers to the European ISO standard 4925 class 6 which specifies the low viscosity rating of 750 cSt @ -40 Deg C.

The one I use is Ate SL6 which is the right stuff and fairly easy to find.

 

[Petrol Pete]

https://bobistheoilguy.com/forums/threads/pentosin-brake-fluid.300591/

Just to confuse things even more.