Folks, Just a general query, when I was flushing the brake fluid in the wife's GLC, I see that it looked for DOT4+ spec'd brake fluid which translates into "buy the MB fluid". I had Pentosin Super DOT4 and in that went. Where has this DOT4+ business come from? If you had standard DOT4 and launched that in, would it really be the end of the world? I believe the DOT4+ has a slightly higher boiling point but realistically for normal driving, does it make a blind bit of difference what DOT4 goes in, particularly if you're going to flush it every couple of years?
I have attempted to explain it years ago, in the days of many trackdays. https://clubgti.com/forums/index.ph...and-super-dot-4-data-comparison-table.268575/
Interesting article and informative, I have done a bit more research and it looks like that fluid viscosity is now coming more into play for vehicle manufacturers, it is in relation to newer ABS modules and getting maximum functionality out of ABS systems especially at lower temperatures. (An important consideration for where I currently reside...) Viscosity of the brake fluid is measured at two points. The first point is at 100 degrees Celsius and the second point is at -40 degrees. At 100˚C (212˚F) most fluids tend to be free flowing and it’s relatively easy to achieve a kinematic viscosity of 1.5mm2/s. At sub-zero temperatures of -40˚C (-40˚F), the fluids tend to “thicken” and it becomes difficult to ensure that it can still flow freely. Most modern vehicles have advanced braking control and traction control and will need to use this technology at frigid temperatures so this characteristic is extremely important in such environments. For this reason, among others, most modern vehicles will use a Super DOT 4 grade since these grades address the need for low-temperature viscosity aimed at reducing ABS cycle response times. There may also be changes within the braking components themselves in that that seals etc. may have been designed for fluids with lower viscosity and may not provide optimum sealing with other fluids.
