Brake fluid - dot 4 or 5.1?

[wid77]

Can someone tell me the correct brake fluid for a 2001 A4 (B4 model) with 115PD engine (if it makes any difference)? My local garage say that they normally use dot 4. Is this ok or would I be better upgrading to 5.1? I don't think it has been changed on my car for at least 3 years and there is a lack of pedal feel.

I am no expert on the differences between these types of brake fluid apart from I was advised to put dot 5.1 in my 1987 Toyota MR2.

Thanks. Wid77

[Niall76]

I'm pretty certain that if you have a look at the Brake fluid reservoir cap it says on it? Or around the cap, mouled into the reservior.

DOT 3 and DOT 4 are polyglycol-based fluids and can be mixed with each other. DOT 5.1 can also be mixed with DOT 3 and DOT 4, even though it is based on a different chemical and has about half the viscosity. If DOT 5.1 is specified for an ABS system, do not add or use any other fluid type. DOT 5 is silicone-based (not less than 70% by weight of a diorgano polysiloxane) and must not be mixed with or contaminated by DOT 3, DOT 4, or DOT5.1.

[Dave Avant]

Most cars have ABS now and they require atleast DOT 4.

DOT 5.1 is considered to be better in terms of coping with more heat etc and isn't supposed to absorb moisture as much. But You may find the pedal is very slightly softer.

A good DOT 4 like Castrol response is good enough.

Also if brakes aren't 'used' harshly once in a while they can become a bit vague a few good high speed presses can perk them up.

[wid77]

Thanks a lot for that. I will go for dot 4. Cheers.