Never used them. If they capture all variables as mentioned by @The Critic, I would trust them.
Brake Fluid - Biggest Neglect, Biggest Benefit
- Thread starter webfors
- Start date
edyvw
$50 site donor 2025
Fluid is not compressible. That fluid deteriorated, but if you have dramatic change in feel, the brakes had air pocket before and it was flushed out now.
- Joined
- Feb 22, 2021
- Messages
- 2,002
I change it every 2/3 years but never felt any difference.
Same. I don't think I've ever had a brake issue caused by deteriorated fluid.
I really don't pay much attention to it, I flush it once or twice in the life of a car. I probably do it every 80K.
I've always wondered how much the fluid mixes? I guess with brake heat, there is a bit of convection forces but those are very small horizontal lines going to the back brakes at least. I was dumping in new fluid into the reservoir often for a rear cylinder that leaked for a week, and when I did the front brakes a while later, I'm pretty sure the front line still had some old nasty stuff in it?
IME: The vast majority of the nastiness is usually closest to the caliper/wheel cylinder.
Absolutely, but I often neglect doing a proper fluid flush during service. If I just refresh the reservoir it's better than nothing and easy to do. Maybe it buys me an extra year?
Rolls Royce "used" to say, every 100,000 miles! Not sure what fluid spec they were using.
Mercedes now says "Every 20,000 miles" Not sure if there is a time (year) requirement.
Anyway, my 2018 MB is just turning over 20,000 mi, so I'm probably going to let the dealership do it.
I'm no longer able to get under the car for that kind of work.
Mercedes now says "Every 20,000 miles" Not sure if there is a time (year) requirement.
Anyway, my 2018 MB is just turning over 20,000 mi, so I'm probably going to let the dealership do it.
I'm no longer able to get under the car for that kind of work.
My Ford Escape manual shows to change the fluid every 3 years.
I have a Speedi-Bleed (pressure bleeder) and do it every 2 years.
My last vehicle (2002 Ford Ranger with 165,000 miles), I changed the fluid
every 2 years and still had the original calipers on it.
I have a Speedi-Bleed (pressure bleeder) and do it every 2 years.
My last vehicle (2002 Ford Ranger with 165,000 miles), I changed the fluid
every 2 years and still had the original calipers on it.
The big thing with newer vehicles is that clean brake fluid is parametric for the abs and traction control to operate correctly.
I use a vacuum bleeder. Often, even with 25+ inches of vacuum, it doesn't pull anything. I give the pedal a quick stab to break something loose and then it flows and flows.
Whatever that "something" is that I broke loose, it proves that brake fluid isn't always fluid.
Whatever that "something" is that I broke loose, it proves that brake fluid isn't always fluid.
With sophisticated ABS and traction control systems in modern cars, the need for cleanliness and dry fluid is probably a lot higher. Plus, DOT 4 fluid has less water holding capacity before phase separation occurs.
edyvw
$50 site donor 2025
MB has to have year interval. In Europe it is strictly based on year interval and it is always every two years.
It is tested during technical inspection before car registration.
- Joined
- Jul 10, 2022
- Messages
- 5,915
I remember being in Firestone many years ago and they recommended a brake fluid flush to a woman. She became upset so I felt I had to interject and tell her it should be replaced every 2 years as the fluid is hygroscopic. She proceeded to slap me in the face saying not to use suggestive words like that
I use Phoenix brake fluid test strips for copper content. Time to change when test strip turns from clear to pink color. Only turned colors once when I was living in hot and humid TX. And water content using meter was above 2% as well.
Still need to flush my GX460. Test are good but it’s still on OEM/factory fill on a 2019. Have a cap and non motiv brand pressure bleeder for lexus/toyota Just need to get it done. Maybe next week…
Last edited:
My Volvos get a brake fluid flush every 12-18 months. The Mercedes every year.
Pentosin Super Dot 4
Pentosin Super Dot 4
Some RR cars used a system designed by Citroen and used LHM hydraulic fluid. This stuff is not the same or compatible with common DOT 3, 4, 5.1 brake fluids. Other models used RR363 fluid and later models used DOT 4. The 363 and LHM fluid systems could hold up to 10 ltr of fluid as the system used it to power the suspension and PS also.
https://www.flyingspares.com/news/p...ic-system-mineral-brake-fluid-ut13741pap.html
I have seen calipers rust from the inside out. My ford focus did that before I learned how to work on my own car. Never changed the brake fluid in that one. My ford flex? Same age and I changed the fluid and the inside of the caliper was in a better condition.
I think I did ruin the calipers when I was retracting the rear calipers by turning them and twisted the rubber dust boot.
I think I did ruin the calipers when I was retracting the rear calipers by turning them and twisted the rubber dust boot.
Just did a full flush on a BMW 3 series, along with replacing the pads. Be aware that for some vehicles, as with mine, it's not just DOT 4, but DOT 4 low viscosity brake fluid that should be used. The majority of readily available brake fluids at your local auto parts chain are NOT low viscosity. After some research I was able to identify Motul DOT 4 LV (Class 6), Pentosin DOT 4LV and ATE SL6 DOT 4 LV that meet the low viscosity criteria and are carried or can be easily ordered by my local auto parts retailers.
The problem with that’s is the bf in the reservoir will be fine but the bf at the calipers will be not so fine.
I change my car’s bf every 2 years. Always have.