[bmw246]

hey, e93 328, dealer called and said I need brake fluid flush/filter. Is this necessary? Car was built in Dec. 2010, I bought in May 2012, has 1500 miles- thanks!

[JuppiOne]

SA usually say that to make a few $, but in reality, it is not necessary, not after 1500 miles, but if dealer will do that under maintenance for free, then i will say it wouldn't hurt, but don't pay for it.

I have some SA keep telling me they can add fuel cleaner to the gas to clean the intake value for $50 (or whatever), what a load of crap, our cars are direct injected!

[E90_boostjunky]

i just made an appt to get mine changed Next Tuesday and i have 66,000 miles

[bmw246]

first time for you?. they called me and told me its due to be done i mean its free isnt it? i have a 2011

[John 070]

It is necessary as a function of time, because brake fluid is hygroscopic. BMW would not include it every 2 yrs. under free maintenance if it weren't necessary (they have their own interest in mind, not yours). Nothing like causing brake components to rust from the inside out, by avoiding the replacement of the fluid. It's not BMW alone, it's any car.

[bmw246]

gotcha, well as long as its free, i didn't know, i buy a new car every year so i usually don't need to do any maintenance

[CharlieBear]

Originally Posted by bmw246

gotcha, well as long as its free, i didn't know, i buy a new car every year so i usually don't need to do any maintenance

lol this guy.

[BMWs4ever]

Originally Posted by bmw246

hey, e93 328, dealer called and said I need brake fluid flush/filter. Is this necessary? Car was built in Dec. 2010, I bought in May 2012, has 1500 miles- thanks!

Do what I did. Buy a brake fluid tester and know for sure if you need one. I just bought one for about $20 and it read less then 1% water in the fluid so I I know I don't need a flush.

I changed my brake fluid at 2 years for free as it was part of the free service for the new car but now at 5 years old I wanted to check it myself before spending the money.

[MrQuickR1]

I just did my front brakes/rotors this past weekend along with changing the brake fluid. The difference in color was amazing. From dark ale color to the new clear yellowish tint. If it's free, have them do it.

[JRJ1970]

My "Brake Fluid Service" light came on this morning. This car is 1 year, 8 months old and has 16,000 miles on it.

This seems strange to me since my 2008 E90 never did this even after 25,000 miles.

[Rydicule]

Originally Posted by JRJ1970

My "Brake Fluid Service" light came on this morning. This car is 1 year, 8 months old and has 16,000 miles on it.

This seems strange to me since my 2008 E90 never did this even after 25,000 miles.

The brake fluid isn't a function of miles. The car could have 100 miles on it, however, still require a brake fluid flush.

The reason to change the brake fluid isn't due to the quality or color of the fluid itself, it's because over time moisture accumulates. While brake lines are sealed pretty well, over time very small amount of moisture contaminate the brake fluid.

At no point in time is this going to cause the brakes to fail... it only makes them less effective. In fact, MOST people drive cars for 5+ years without ever changing the brake fluid because the decline in brake effectiveness is so subtle over time. However, if you took on of those cars and changed the brake fluid, it would make a noticeable difference in the pedal feel during braking.

BMW recommends 2 year intervals because that's what they feel is the appropriate amount of time their standard fluid can perform at the level they consider standard for their car brand. The car will not blow up or even lose any reliability if you decide to forgo the service.

[bmw246]

i ended up getting it, now if you could help me with my battery problem...

[adiba14]

How much does the dealer charge for this approximately??

[gpb]

Originally Posted by BMWs4ever

Do what I did. Buy a brake fluid tester and know for sure if you need one. I just bought one for about $20 and it read less then 1% water in the fluid so I I know I don't need a flush.

Does water propogate through the fluid evenly? i.e. is testing it in one spot (such as the master cylinder resevoir) valid for the fluid condition in all the calipers as well?

[Kolyan2k]

2-3 year intervals are fine

[3er BMW]

Originally Posted by gpb

Does water propogate through the fluid evenly? i.e. is testing it in one spot (such as the master cylinder resevoir) valid for the fluid condition in all the calipers as well?

As mentioned brake fluid is hygroscopic absorbing moisture from the air
thus lowering the boiling point.
And yes it will eventually cause brake failure due to pockets of steam in the brake lines etc.
This can happen e.g. going down a mountain with long periods of brake
application.

[Bobble]

Some intreresting things said here, but the main reason to change the fluid is as it retains moisture the water will not compress like true hydraulic fluid and the brakes will not be as effective due to not pushing as much hydraulic fluid thru the system.

I have never boiled brake fluid on a street car, only on the track. If you are seriously concerned about boiling your brake fluid go to DOT5 silicon racing fluid as that is hydroscopic and does not boil until over 500 degrees but has other issues and that's way most dedicated track cars change fluid often.

Also most DOT approved, in fact all of the ones that I can think of have corrosion inhibitors so to rust your brake parts internally you'd need to run a long time with a lot of water in the fluid and you'd really notice braking degradation I would hope first.

Do it every 2 years, it's not that costly and easy to do if you are somewhat handy.

[avocet]

Hydraulic fluid is just as noncompressible as water. Or else we would have very very spongy brakes.

I will change fluid every year. Just use a turkey baster and suck what I can out out of the reservoir. Keeps the fluid fresh until a brake pad service. Then it gets a flush.

[raceyBMW]

Problem when you get water in the brake fluid is that the water will easily boil, and when it boils it places air bubbles into the system...air obviously is much more compressible than the fluids, and this is why it gets spongy feeling.

Also, water is corrosive to the break lines.

[Efthreeoh]

Brake fluid slowly absorbs water. It absorbs the water vapor present in air. The brake system is not sealed closed, so air is present in the master cylinder reservoir. If the system were sealed closed, as the brake pads wear and create space in the cylinders of the calipers, a vacuum would be created, which would eventually lock the system and make it not work.

Water in the fluid lowers the maximum boiling point of the fluid. When the fluid "boils" is now contains brake fluid in a gaseous state (not a liquid state - remember states of change: gas-liquid-solid - from high-school chemistry?). Once in a gaseous state, the fluid becomes compressible and does not transfer force from the master cylinder to the calipers as well as fluid in a liquid state.

And by the way to the OP, there is no "filter" in the brake system to change. Brake fluid is not like engine oil.

[gpb]

Originally Posted by 3er BMW

As mentioned brake fluid is hygroscopic [...] going down a mountain with long periods of brake
application.

All very true, but none is relevant to my question. Does testing the water content in one place such as the master cylinder reservoir validly tell you the condition of the fluid throughout the system?

Originally Posted by avocet

I will change fluid every year. Just use a turkey baster and suck what I can out out of the reservoir. Keeps the fluid fresh until a brake pad service. Then it gets a flush.

I don't understand this; how does changing the master cylinder reservoir fluid freshen the fluid in the lilnes and calipers?

[F1 Fanatikko]

Originally Posted by adiba14

How much does the dealer charge for this approximately??

around $180 thats included parts and labor.