sonyfever

My maintenance reminder is showing B7 at low 20k miles, suggesting a brake oil change. I thought that was early, and wonder whether I use the brake too hard. When do you guys have your first A/B7 service?

hans471

OK, for the record its NOT brake oil (least not on this vehicle), its brake fluid! No problem...just want to be clear.

Normally changing of brake fluid has more to do with TIME than usage. Brake fluid attracts moisture and that causes chemical reactions and rust in the system. Most recommend changing the fluid every three or so years, more often if its color starts to darken."Brake fluids are composed of 3 mains components


SOLVENT 60 to 90%

Polyglycols have a high viscosity that is why it is necessary to dilute them with a product with low viscosity (polyglycol ethers).
Polyglycols ethers ensure the role of solvent in the fluid. They have to dissolve polyglycols and all other components in such a way to obtain a single-phased fluid to provide satisfactory lubrication under all temperatures.

LUBRICANT BASIS 5 to 30%

Polyglycols are used as lubricants in proportion of up to 30% in brake fluids.
They are obtained by reacting alkylene oxides (ethylene and propylene) with bifunctional components such as diols or water.

ADDITIVES 2 to 5%

Brake fluids usually contain up to 5% of additives.
Corrosion inhibitors are added to protect the brake system metals from corrosion and antioxidants are needed to reduce the oxidative decomposition of glycol ethers polyglycols and to retard the formation of acidic decomposition products and resins.
These two inhibitors' types are essential to ensure a long-term and satisfactory brake fluid service life."

anoop

I'm at 25K miles and it's at 20% oil life showing B 1 2 7. The car has been in service 2 years and 6 months.

sonyfever

Thanks, that is reassuring.

Thanks for the info, no wonder when I typed brake oil I felt something was wrong. Those liquids do look similar to me!

alexanderowen

Hi, my B7 notification came up on my instrument panel. My car is at 100000km, what does that entail? It’s a 2016 CLA 200.