Depends where you are. Brake fluid sucks up humidity. It's all ways damp where I am. So I change it in everything. The brake systems now are far more complicated.

Moisture from your brake fluid can cause failure - Douglas Automotive

Over the past few years, I've had an auto repair shop tell me the brake fluid needed to be flushed in the car since the oxidation level was high. Is this something that needs to be done, or is really unnecessary?

www.douglasautomotive.com

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I had Honda's for over 20 years before moving to my OBW and they recommended the change at 60,000 miles - my problem will be I took delivery of my OBW on February 4th - I have 8500 miles now, I will reach 30,000 before the end of the year, less than 12 months from the vehicle being put into service, and over 60% of my miles are highway - I am going to do the change, as that is what is recommended and my plan is to drive the vehicle until the wheels fall off, so I understand your dilemma...................

 

brake fluid deteriorates with time not mileage per se. Mileage is only a metric as it informs time. go get it flushed and changed. Its only your life we are talking about.

 

What I did was buy Speed Bleeders since I don't have helpers anymore and a quart of brake fluid. About $30.

 

Honestly NO. Sure the fluid will eventually get contaminated, But the side effects of that are small. it should be changed, but honestly you wont run into problems related to this for 150k miles or so. If your a very aggressive driver, the fluid could over heat and burn. But i mean "drive it Like you stole it" type driving. if you were to change every 100k, under normal Circumstances, it would be fine. I've Noticed a few things that are recommended as routine services, have a "generic Safe" Mileage recommendation. I see it with Many different Brands, other then Subaru as well.

 

Owning an auto shop you're my favorite type of expert. I get bigger tickets and more 'have to have done now' work from customers who listen to folks like you. Please, keep on doing what you're doing.

For those of you who don't think auto repair shops are ALL out to get you...My advice? Find a shop that is a BG dealer for fluid flushes. BG subsidizes warranties on all lubricated parts that you flush/service with their products with a two tier plan. 50k and under and 100k and under. Flush the brake system at 49k and if you have a master cylinder fail in the next 30k you'll have up to $2k to cover the replacement. Same goes for GDI engines, differentials, CVT's, Power Steering, Coolant, Transfer Cases. That's how confident BG is in their services/products and I fully endorse them. I sell a lot of flush services out of my shop because I believe in them and their best in class chemistry. My family drives vehicles that are ALL seven to twelve years old - all of them flushed/maintained and they all have zero problems in their systems covered by BG maintenance. (And if anyone cares - run a GDI service every year or 12k. Don't wait until your spark plug interval service arrives. You'll thank me later. Every GDI car is prone to carbon buildup from this injection process on the valves.)

 

What are speed bleeders?

 

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I change the fluid when I change brake pads since it is easy at that time and makes pushing the caliper pistons back in easy also. im not in a humid area though.

 

I would avoid offering this as advice because driving habits are very different. If I'd followed that on my previous car, I would have gone 200k miles and 15 years without ever having changed the fluid, because I never once changed the front pads. No thanks.

I don't agree that 30k miles makes sense, but it should be done at some point...5 year/50k? Don't neglect the rubber hoses either (but that's hopefully years away from now).

 

Depending on location/humidity etc, for most people every 3 years is plenty.

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Blanket statements about brake fluid are unhelpful because conditions are different for different areas of the country - brake fluid can be tested for moisture content but actual boiling point testers are better vs conductivity electronic testers that may not be accurate.

As with anything in the maintenance schedule, it's conservative and a "better safe than sorry" best practice type of thing that will keep 100% of cars doing just fine but if you delayed it, 90% of cars might be just fine. Another consideration is whether or not this is a car you will get rid of in a couple years, or if you might keep it longer. If you are going to keep the car for a very long time then just doing the fluid change will give you more confidence going forward, you don't want corrosion in the ABS system, which may take years to develop but if it does, it's not fixed by a normal fluid change because fluid is stuck in the ABS system unless you do special things that force the ABS system to pump.

Here's Underhood service's take: Brake Fluid Testing: Bleeding and Flushing Minimizes Internal Corrosion in the Brake System

 

It's a chronically ignored maintenance item and rarely causes issues, even with modern vehicles (according to mechanics I know in the NY metro area). I'm in the 3-5 year camp for the first change (but I accept that may not be optimal).

 

I'm in the 3-5 year camp for the first change

Agreed, I live in NorthEast where the summers are very humid.

I have seen what happens when brake fluid is ignored too long. The fluid gets saturated with moisture (think of a wet sponge) Then, when the ambient temp. gets cold in the winter, the water precipitates out of the fluid and works its way to the lowest points of the braking-system. (the calipers)

The water in the calipers causes corrosion... after some time, the calipers fail. Replacement is expensive.

On the other hand:
If the brake fluid is changed every 3-5 years, the calipers will last the life of the vehicle.

 

I have seen people on here suggest that you can suck the fluid out with a turkey baster and replace it with new fluid if you do not want to go through the trouble of the full procedure.

 

those posters probably have snoods.

 

Yes.

My 01 VDC has its original calipers are 237k miles. Flushed on 2 year intervals.

And every time after the flush, I can tell the difference in pressure.

 

Yes.

My 01 VDC has its original calipers are 237k miles. Flushed on 2 year intervals.

And every time after the flush, I can tell the difference in pressure.

Is there a reason why you felt the 3y interval wasn’t enough? Did you test your fluid after 2 years for moisture?

 

They make brake fluid testers to measure the water content for under $20. You could get one and really tell if it needs changing.

 

I bought this with skepticism as a cheap tool providing interesting results. https://www.amazon.com/gp/product/B076SC377J/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I found it odd had almost 5 stars so I had to check it out. My OB with 16k miles came back perfectly green, 0%, I had never opened the brake fluid until that moment. My GF's Ridgeline which just had a dealer brakeflush, 3%! I went to Autozone and tested
a cup of freshly opened Autozone brand dot3, 2%. I took the truck back to the dealership to explain my findings and would they be willing to test a couple brand new cars with me? They straight up just did
another flush without any testing. Came back 2%. I know Subaru puts out quality lubes, coolant ,etc. but I'm still testing to find another perfect 0%.

 

That's why conductivity testers are unreliable

 

Thanks much for the input. I guess I'm getting schooled here. I've been driving for 50 years now and NEVER completely flushed a brake system unless I had catastrophic loss of fluid/ and component changes. I've also have very few failures of calipers and such due to corrosion (and those were on vehicles that got backed into the ocean to launch boats.) . To be honest, I've never even heard of flushing the brakes as routine maintenance. That said, I know systems are more complex these days and likely made of cheaper materials so I won't ignore the 3-5 year rule I'm hearing repeatedly here. I'm at 31K mi but still 6 mos short of 3 years. I don't live in a super humid environment and the car is garaged so I think I'll just hold off and have my tire dealer do a flush when he puts on my new tires this fall.

 

Another data point, my wife's 2001 Avalon which we bought new, has never had anything done to the brake fluid. Just pads replaced, still original calipers and disks. It does have anti-lock brakes, they still work fine.

I'm afraid to flush it now, the brake lines go into the caliper/cylinder in one place and the bleeder is in another place, so if I flush it, all the goop in the lines is going to fall out in the wheel cylinders before it gets to the bleeder outlet, lol.

 

That's odd, the have not touched the brake fluid on my wife's 2018 Crosstrek, and she takes it in for everything because it's free. Guess I should test the fluid myself and see what's what.

 

I purchased a brake fluid moisture meter years ago from Amazon. I periodically check the fluid moisture content. 36,000 miles on my Ascent with no significant moisture. Thirteen year old Mazda Miata with no moisture. All with original brake fluid. I'm not going to replace it until I get moisture in it.

 

Brake fluid is cheaper than a stuck caliper....

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Just to be clear, I,m not recommending not changing the brake fluid. Just reporting about one Avalon's history. I fully intend to follow the Outback's recommendations now that I've been enlightened.

 

On my older cars must confess I have neglected brake fluid changes - the only time ABS engages is once every 5 years. But in new cars with brake based torque vectoring the braking system is constantly active and if it gets mucked up I'm afraid the consequences are worse.

 

Do yourself a big favor and flush the system every 2-3 years (another 50+ year driver here. )

 

Under warranty, follow Subaru's guidelines

Brake fluid should be charged every 3 yrs regardless of mileage. It's a good idea to have your brakes annually in any case.
Tires: Change at 5-6 years or 5/32 (snowy areas) or 4/32 (other areas)
Oil, is mileage/operating hour dependent, not time. Oil on Gen6 Outbacks typically needs to be changed more often due to fuel in the oil, common with DI engines. Have your oil analyzed to see if it a problem for your specific driving conditions.
Other fluids and spark plugs are mostly mileage/operating hour dependent.
Belts/batteries are dependent on mileage/operating hours and time
Hoses and plastic/rubber parts and brake lines, mostly time, and conditions.

 

That tool is no better than using a Digital Multi-Meter, set to the lowest voltage setting. You put the Black lead against the battery ground, and dip the Red terminal into the fluid. If it isn't <.3 volts (3 micro-volts), there's too much moisture in the system. - Probably more accurate than using the AA/AAA cell between two terminals, however, I'd still change the fluid every 30k as recommended.

If your driving is really low, think about changing it between 3-4 years, since fluid is cheap, and replacing lines, calipers, or worse a master cylinder/ABS pump is rather expensive.