Is there any practical (or even minor) differences between dot 4 LV fluids? Any that offer any type of advantage over the competition or are they all basically the same despite some surprising price differences?
Dot 4 LV differences?
- Thread starter buck91
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Impossible to know, sadly. Some will be more benign to seals than others but even batches of the same product can have variances.
Look into the Bosch brake fluid and its viscosity despite it not being labeled as a DOT4 LV brake fluid.
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There are tiny differences in boiling temperatures and densities but nothing you'd notice in real life. DOT 5.1 is the way to go though, specifically Bosch ESI6. It has the lowest viscosity and slightly higher boiling temperatures than even ATE Super DOT 5.1. Both have a 3 year service life, compared to 2 for DOT4 and 1.5 for DOT3 (per Bosch).
https://www.boschautoparts.com/documents/647135/656981/ESI6 Brake Fluid Flyer.pdf
https://www.boschautoparts.com/documents/647135/656981/ESI6 Brake Fluid Flyer.pdf
Dot 4 LV and others similar designations 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.
Often you’ll see them marketed as DOT 4 LV + class 6 which refers to the European ISO standard 4925 class 6 an that specifies the low viscosity rating of 750 cSt @ -40 Deg C. I would have thought any low viscosity brake fluid that meets this standard will be good.
Combining the North American standard DOT 4 with the European ISO standard class 6 is a bit of a mess especially when you throw in different marketing terms but there is no DOT standard for low viscosity fluids. In fact the lack of a DOT standard is why there are so many different marketing designations for low viscosity fluid.
This new Bosch ES16 Dot 5.1 isn't as quite as thin as the Class 6 standard but the difference may not be worth worrying about. Also it's the first time I've seen a 5.1 fluid claim to have a longer life. Previously 5.1 needed changing more often than DOT 4 because it absorbed water faster.
Often you’ll see them marketed as DOT 4 LV + class 6 which refers to the European ISO standard 4925 class 6 an that specifies the low viscosity rating of 750 cSt @ -40 Deg C. I would have thought any low viscosity brake fluid that meets this standard will be good.
Combining the North American standard DOT 4 with the European ISO standard class 6 is a bit of a mess especially when you throw in different marketing terms but there is no DOT standard for low viscosity fluids. In fact the lack of a DOT standard is why there are so many different marketing designations for low viscosity fluid.
This new Bosch ES16 Dot 5.1 isn't as quite as thin as the Class 6 standard but the difference may not be worth worrying about. Also it's the first time I've seen a 5.1 fluid claim to have a longer life. Previously 5.1 needed changing more often than DOT 4 because it absorbed water faster.
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There are some differences in wet boiling point but they may not be material.
The main advantage to DOT4LV is the cold temp performance and overall viscosity curve.
There are also somewhat similar differences within DOT3 fluids but most people are not aware of it.
The main advantage to DOT4LV is the cold temp performance and overall viscosity curve.
There are also somewhat similar differences within DOT3 fluids but most people are not aware of it.
DOT 3, DOT 4, etc are standards so at a minimum, any brake fluid labeled as such will meet the US Dept of Transportation's specifications. Any variations in formulation a) can't impact meeting the spec and b) will have minor improvements, if anything.
As you’ve said, there are minimum standards - but there is nothing that says performance cannot be improved upon.
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As far as I know, ISO 4925 Class 6 specs 750cst at -40C while the Bosch ESI6 is 685cst. Other DOT 5.1 fluids may only be 900cst though
