DOT 5.1 Brake Fluid Compatability (2024)

Woodleigh

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Wighty said:

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

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Woodleigh

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Forgot the photo

robin.large

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

Sent from my ONEPLUS A5010 using Tapatalk

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richlumb said:

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

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Woodleigh said:

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 .

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Woodleigh said:

Forgot the photoView attachment 63811

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

4 & 5.1

4 & 5 , naaaa

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  • Nov 29, 2020
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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.

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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"

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Woodleigh said:

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

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