Brake Fluid


Information and questions on GL1800 Goldwings (2001-2017)
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bstig60
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Brake Fluid

Post by bstig60 »



Will it hurt to mix synthetic Dot 4 with regular brake fluid in the GL1800 brake system?


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baumedagn
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Re: Brake Fluid

Post by baumedagn »

I don't know if it will hurt or not, but I would just flush out the old. Why take the chance?
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Re: Brake Fluid

Post by Viking »

All Dot 4 brake fluid is synthetic, as are Dot 3 and Dot 5.1. The only petroleum based fluid is Dot 5. They say you can mix any of the synthetics together, such as 3 with 4 with 5.1, however, you will get an unpredictable boiling point. I would NOT do it tho. But 4 with 4 is just fine. It has also been said that you can clean out Dot 3 and replace with Dot 4, but you cannot clean out Dot 4 and replace it with Dot 3. (?????? why not if both are synthetic and can be mixed together) There is a lot of good and bad info on brake fluid to be found, but the mixing of Dot 4 with Dot 4 is not one of the bad ones.
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Re: Brake Fluid

Post by tamathumper »

I just replaced all of my brake fluid with a big ol' bottle of "DOT 3+4".

So either I'm screwed, or it's from the future and it's actually DOT 7.
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Re: Brake Fluid

Post by Viking »

tamathumper wrote: Thu May 02, 2019 5:52 pm I just replaced all of my brake fluid with a big ol' bottle of "DOT 3+4".

So either I'm screwed, or it's from the future and it's actually DOT 7.
It is from the future and can be used in place of either 3 or 4. It is likely Dot 4.
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Re: Brake Fluid

Post by keithg64 »

Actually dot 3 & 4 & 5.1are all glycol based and the 3 & 4 I know are interchangeable. The dot 5 is synthetic and is not interchangeable with the others. The 5.1 is a glycol base with a higher heat range.
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Re: Brake Fluid

Post by keithg64 »

It's not what you buy, it's what you build.
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Re: Brake Fluid

Post by Viking »

keithg64 wrote: Sun May 05, 2019 2:01 pm Actually dot 3 & 4 & 5.1are all glycol based and the 3 & 4 I know are interchangeable. The dot 5 is synthetic and is not interchangeable with the others. The 5.1 is a glycol base with a higher heat range.
Actually "glycol based" does not mean they are not synthetic. It means they are synthesized from a glycol. Dot 5, in your link says Silicone based which is why it is not interchangeable with the other three. In my post above, where I stated that only Dot 5 is petroleum based, that also should have said SILICON based. Slip of the fingers before engaging brain. :lol:


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