DOT 5.1 Brake Fluid Compatability

[Woodleigh]

https://www.opieoils.co.uk/p-121353-fuchs-maintain-dot-51-ultra-high-performance-brake-fluid.aspx

Hello all,

I just need some reassurance; I've ordered 2 litres of Fuchs DOT 5.1 brake fluid from Opie Oil.
However, I have just looked in the hand book which recommends MB 331.0 DOT 4 brake fluid for my W205.

So my question is will the DOT 5.1 be OK in my car.

 

[Wighty]

https://www.opieoils.co.uk/p-121353-fuchs-maintain-dot-51-ultra-high-performance-brake-fluid.aspx

Hello all,

I just need some reassurance; I've ordered 2 litres of Fuchs DOT 5.1 brake fluid from Opie Oil.
However, I have just looked in the hand book which recommends MB 331.0 DOT 4 brake fluid for my W205.

So my question is will the DOT 5.1 be OK in my car.

I don’t believe they should be mixed , the brake fluid reservoir cap usually also confirms the spec . I vote no

 

[M80]

What's the difference between DOT 4 and DOT 5.1 brake fluid? | Epic Bleed Solutions

I hope this is right cos it's going into mine.
The fronts are done but it's raining again so maybe tomorrow for the rear.
Tbh I would have bought DOT4 but wanted more than 2 litres and the 5.1 in 5 litres was the right price.

 

[richlumb]

I Once changed a previous cars fluid to 5.1 and I flushed the system but I also changed to braided hoses so the system was half way there

 

[Woodleigh]

I don’t believe they should be mixed , the brake fluid reservoir cap usually also confirms the spec . I vote no

Hello Wighty, I have just taken a photo of the cap (please see attached) and it says Use only DOT 4 +, whatever the + means.

Meanwhile I have had this response from Opie Oil: -

Hi Mike
Yes, the 5.1 is ideal, it's an upgrade over the DOT4.
Regards
Tim

 

[Woodleigh]

Forgot the photo

 

[robin.large]

Fully compatible/mixable. 5.1 just has higher boiling point.

Sent from my ONEPLUS A5010 using Tapatalk

 

[Woodleigh]

Fully compatible/mixable. 5.1 just has higher boiling point.

Sent from my ONEPLUS A5010 using Tapatalk

Thanks Robin

 

[Woodleigh]

I Once changed a previous cars fluid to 5.1 and I flushed the system but I also changed to braided hoses so the system was halfway there

Good plan Rich, think I'll flush mine at the 'B' service

 

[Wighty]

Hello Wighty, I have just taken a photo of the cap (please see attached) and it says Use only DOT 4 +, whatever the + means.

Meanwhile I have had this response from Opie Oil: -

Hi Mike
Yes, the 5.1 is ideal, it's an upgrade over the DOT4.
Regards
Tim

Good to know buddy , every day is a school day . Apparently it’s dot 5 that can’t be mixed it’s silicone based , not glycol based .

 

[Gazwould]

Forgot the photo View attachment 63811

Classic example of how things and handbooks get stuck in time .

4 & 5.1

4 & 5 , naaaa

 

[davidsl500]

Put Dot 5.1 in My X type once and soon changed back to Dot 4. The pedal feel was different - felt there was a lot more travel.

 

[Woodleigh]

Just read on another forum; the guy says it sounds strange but true..."Always buy brake fluid that come in sealed metal containers as the plastic containers absorb water"

 

[Wighty]

Just read on another forum; the guy says it sounds strange but true..."Always buy brake fluid that come in sealed metal containers as the plastic containers absorb water"

Don’t worry about that , brake fluid doesn’t sit on the shelves for years , it gets bought and used . Maybe think twice about an open container from the garage that is years and years old