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Discussion Starter · #1 ·
I was reading a Haynes Repair Manual I got for Christmas (2004 Subaru Forester). I noted it calls for changing the brake fluid every 30,000 miles. I blogged on this subject a bit on the Impreza Forester forum and was convinced my long time practice of never changing the brake fluid (even on a car that I ran for 200,000 miles) is unwise and unsafe. Welcome views on that conclusion.

So, I am thinking about buying a vacuum hand pump for speeding up the change of the fluid, i.e., suck the fluid out at each wheel until it runs clear/fresh. I understand one can simply let it drip, that is open the bleeder port and just let it drip into the catch pan... of course not pumping the brakes and making sure the master cylinder remains near full. This noted, I don't know if one has to leave the master cylinder cap "ajar" so air can leak in to let the fluid gravity feed back to the open bleeder valve.:drunkie:

Also, what to due with the old brake fluid, it can't go into my engine oil recycle I'd guess. :thThumbsU
 

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I've never changed the brake fluid in my cars/trucks, not saying I shouldn't have just never did.
On the other hand, I'm anal about changing it in my bike, why...more than likely because I can see it thru the sight glass turning a nasty brown with the absorbed moisture, brake fluid is hygroscopic (absorbs moisture). I use a hand vacuum pump and it's very easy, used to take 10 minutes on my previous ride a Kawi Vulcan 1500. My curent, a Goldwing takes a bit longer because of having to remove the tupperware but I still do it.
I'd check into it to make sure you can use a vacuum pump, nowdays with all the anti-lock, traction control etc I wouldn't be sure if it's a clear path back to the resevoir.
As for the old fluid, I collect it with my waste oil and use it to start brush fires.....Mike
 

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Discussion Starter · #3 ·
Brush fires, sounds like a good way to get rid of petroleum waste, I guess:howdy:

I pulled my owner manual, I purchased the car new. Yes, it calls for changing the brake fluid every 30,000 miles (USA) - more frequently if under severe service. I'll double check with the folks on the Subaru Impreza (Forester) forum. I have exchanged some posts there and got a bit of a lecture (wasn't call stupid, but close - could be true) and I recall one said I could just let it drip if I had the time. Another low cost method is to connect the bleeder valve to a container with a poly tube that is attached such that it is held under some brake fluid in the container. Then one can go slowly pump the brake peddle. This I can easily understand as in the past, years past, when I had to bleed brakes (soft peddle) I had my wife sit in the car and pump the peddle while I had the valve open, holding the peddle down until I closed the valve. The tub/container keeps air from being sucked back in due to the tub outlet being below fluid level in the container. I kind of like this method, but the less than $50 vacuum, which can be used for other tests, has some appeal.

It seems popular, especially at the Subaru dealership, to change the auto transmission fluid. This is not called for in the Subaru manual. There is no call either to change the differential oil, but the dealer would like to... a high profit margin item as the mechanic doing the job can be an entry-level skill.
 

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I change Auto trans fluid every 30K miles, as well as a new filter...on everything I own.

Brake fluid...When it get dark or smells burn...Ill drain the resevoir and add fresh...but Ive only ever "change my fluid" once and it was only because I came down to 45 from 130 too fast and boiled the fluid in the calipers on my vette and had black fluid and alot of air in the lines.
 

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dirtgeezer
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I buy a cheap turkey baster (giant eye dropper) and suck the old fluid out of the reservoir add new fluid, don't pump the brakes just suck the old fluid out and pour in some new. Throw the turkey baster in the trash after you wash it out with soap and water.
 

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Discussion Starter · #8 ·
Wow, some nice responses, now I know I am not the only ---- who doesn't or hasn't changed brake fluid. I never even noticed it was called out in the Forester owner manual maintenance section. I think I said, think I'll change it, but the idea (Thanks Red - nice Mustang - what year is that? looks new) of just sucking the reserves out and putting in fresh.. but how fresh. How about a sealed, but has been opened and some used, can on my shelf that is a few years old. Yes, I don't go through much brake fluid, good news. I understand one should dump, due to absorbing water from the air once opened, any fluid over a year old. In NJ we have lots of humidity. I think it is the water in suspension in the gas that lowers the boiling point... it take "free" air in the line to give one a "soft" peddle. Is Dot 4 better than Dot 3? That could be a reason to dump my old Dot 3. Then, the manual also warns not to mix brake fluids, is Dot 3 and Dot 4 considered mixing? Why so many questions? Like can't be this complicated, must be my old age.

I may pass on the transmission adder here, my Forester manual doesn't call for transmission fluid change.
 

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Probably the best way to change the fluid is to have someone "pump up" the brakes while you open the bleeder. Make sure to close the bleeder before your helper lets his/her foot off the brake. Repeat 2-3 times for each caliper or brake cylinder. This removes the old/crappy fluid from the business end of the system. Don't let the master cyl get low while doing this or you will just add air to the system.

The hardest part of the above is just breaking the bleeders loose. In salt country (MN/Wis) this can be quite a chore on older vehicles.

Jim
 

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Change brake fluid every 3-4 yrs on 4 vehicles i'm responsible for.

Exercise caution to not let master cyl run out while flushing system. I had this happen with a '05 GTO with ABS and it was a challenge to make things work properly & code free.
 

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I have never made it point of changing brake fluid as a seperate job but always give a few extra bleed cycles when doing hydraulic brake work (calipers, hoses, or wheel cyl.) As the previous post stated dot 5 is not compatible with dot 3 or dot 4 which are both glycol based. In recent years I have purchased fluid in smaller containers to avoid the moisture contamination issue. Another caution is be careful with the fluid around painted and some plastic surfaces. It is one of the best paint strippers there is.
 

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I change the brake fluid in both my vehicles every two years. I drain the master and refill it with fresh fluid and then gravity drain it at each caliper. The ABS on the '03 Dodge offers no problem doing this. I don't believe DOT 5 is compatible with ABS, but it is a popular motorcycle fluid as it won't damage the paint finish. DOT 5.1 is another option for ABS vehicles.
 

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you can start bleeding by opening the bleeder before pushing pistons back in . then I use a vacuum pump .I don't have corrosion problems as much that way, moisture in the lines does a lot of damge.
 

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I dont really make it a point to do exact service interval on brake fluid but I do change it when it starts to smell or turns strange colors. It's one of those things that has had more hype in recent years than before, kind of like people who flush their coolant every 6 months. It's recommended by a lot of shops but it seems more like a sales gimmick than anything else.

Anyway just grab yourself about 2 quarts of fluid and start at the corner furthest from the master cylinder. Make sure to keep the reservoir full during this process. Have a buddy pump the pedal, or have him do the bleeder end if you dont like him much. I start at the passenger rear and just go about bleeding the brakes until the fluid runs clear. Check the reservoir then I move to the drivers side rear, same thing. Check reservoir again then do same to passenger front. Check again and finally do drivers side front. Once you're done top off the reservoir and you have successfully flushed out and changed your brake fluid. If you have a larger vehicle or something with overkill brakes, check the reservoir more often during the procedure as some vehicles empty the reservoir faster than others.
 

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I just changed the brake fluid in my Ram. Of course I had no choice after the heat from the exploded wheel bearing caused the seals in the caliper to melt :)
 

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Another advantage to changing brake fluid on a regular basis is that it keeps the brake bleeders operable. Changing brake fluid is a cheap option compared to the cost of calipers, master cylinders or ABS units.
 

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Discussion Starter · #19 ·
Synthetic??

Okay, I'm sold on changing the brake fluid.

Today I walked by the Walmart auto stuff, I think they are fine source for oil and the like. What I found was a little surprising. I found Prestone Dot 3 only in Synthetic. They had their own brand Super Tech Dot 3 non-synthetic (didn't say synthetic in any case) and it was the same price as the Prestone Synthetic, go figure.

So, if I go synthetic that means I will most likely be mixing, to the extent that I don't purge the total system of the original Dot 3, synthetic with an earlier version of Dot 3, 2004 built Subaru. Is this a concern?
 

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Synthetic??

Okay, I'm sold on changing the brake fluid.

Today I walked by the Walmart auto stuff, I think they are fine source for oil and the like. What I found was a little surprising. I found Prestone Dot 3 only in Synthetic. They had their own brand Super Tech Dot 3 non-synthetic (didn't say synthetic in any case) and it was the same price as the Prestone Synthetic, go figure.

So, if I go synthetic that means I will most likely be mixing, to the extent that I don't purge the total system of the original Dot 3, synthetic with an earlier version of Dot 3, 2004 built Subaru. Is this a concern?

All brake fluid is synthetic. It's not a naturally occurring substance. If it says synthetic on the label, it's strictly for marketing purposes.

Someone also questioned how to dispose of brake fluid. That depends. Many places will allow it to be mixed with waste oil. You'll have to ask your favorite recycler.

Also, it's been mentioned several times that DOT5 silicone fluid can't be mixed with DOT3 & 4. You may not want to mix it but it can be mixed. It's actually specified in the Military brake fluid specs (which is where the DOT specs come from) that they all have to be compatible. The spec number just states boiling points not fluid composition.
 
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