Thanks to all. Information has been forwarded.
Well, you know me. I always have to go for the mild comedy. 
I know Rick is real, because I’ve met him. I’m not sure about me.
Brake fluid is not oil at all. The vast majority of brake fluid in modern cars (DOT 3 and 4 stuff) is glycol ether-based. Oil is specifically not used because would swell and deteriorate the rubber parts of the hydraulic system (seals and such).
Glycol ether fluid also has the benefit of being hygroscopic. Yes, on first thought it seems that absorbing water is a poor quality, because it necessitates changing the brake fluid on a time-based interval. But it’s actually a blessing in disguise, because the alternative is not absorbing water. Water is going to get into the system no matter what, and if it’s not absorbed, it stays unmixed. Then, it can migrate to the business end of the braking system, where it can rust components or boil when things get hot. That’s what can happen with silicone DOT 5 fluids. Hygroscopic fluid, on the other hand, “hides” the water relatively safely in solution at the expense of a somewhat reduced boiling point. The reduced heat tolerance and increased corrosion potential is still there, but is much less severe than in cases where water collects in a hydrophobic system.
So brake systems should ideally be flushed every couple of years regardless of mileage, because their propensity to attract water is only a function of time. It’s true that most cars on the road go far beyond this interval with no real problems, but that’s just a testament to the margins engineered into modern braking systems. It’s still a service that shouldn’t be neglected, because to do so is asking for problems farther down the road. And are brakes really something you want to take chances with?
Nah, it was a Lotus. Too light to need power steering. Too light to need power brakes, in my estimation, but they didn’t listen to me on that one.
The service schedule called for replacing the brake fluid every year. Now, it wasn’t a fair example for this thread, as I took that car to the track. But at the end of each year, when I flushed out the brakes, the fluid that came out was nasty, and brake pedal feel was noticeable better after the service. My current BMW calls for replacement every year as well, but that’s part of their “free” service, so I let them handle it and I don’t know what the fluid is like when they drain it.
Flushing the brake fluid is useless. Calipers usually fail where the piston goes through the seal. Often this is due to the boot getting old and losing elasticity. It never touches the fluid until the seal start leaking.
After 11 years, the boots and seals may be getting old and worn. Perhaps the brake hoses too. Maybe rebuild/replace the hoses and calipers. That can’t be done without losing most of the fluid.
Brake fluid *does *pick up moisture. This is why you will see both a dry temperature rating and a wet rating on every bottle of fluid you buy. You can assume to be operating at the wet rating after one year, or sooner.
You are correct that for most people flushing the brake fluid is useless. This is because most shops that service brakes will not just change the pads but will quote for new or rebuild calipers to be changed at the same time, so the life of the calipers is not an issue.
The thing to consider about the brake system is that it is not a loop where fluid is circulated. The fluid in the calipers and lines stays there and becomes contaminated. I have a car that is no longer made and that I intend to keep forever, so I change my fluid once a year, and yes I know that is overkill, but it only costs me about $10 to do. I use a Mityvac pump so I can suck the fluid through the lines without the old pump-bleed method.
The dark, shitty looking stuff that comes out at the begining looks nothing like the stuff in the resevoir and has made me a believer in brake fluid changes.
I would take issue with your comment about most shops selling calipers as a matter of course.
In all of my years in this business only the bottom feeding chain shops do this.* Quality shops only sell calipers when needed. At my shop IIRC we have sold a grand total of one caliper since Christmas. It was leaking after only 225,000 miles.
*When you hear the ad “Nobody does it like Midas”. This is what they are talking about.
Oh, I agree Rick. That is why I said they will ‘quote’ for calipers. And for turning the rotors, which only needs to be done if they are grooved and weakens them. But people do go to these chain shops to get work done and often the quote is for new brake pads, rebuilt calipers and turning the rotors.
We have a nice tire chain in the NW, Les Schwab, great service, good prices. They also do brakes and always quote for pads, calipers and turned rotors.
Like I said, they are a nice place to buy tires.
In the common single piston caliper, the piston rides in a slightly over size bore, but only touches the seal, a square cross section ring that fits in a groove. When you apply the brake, the piston pushes the inner pad against the rotor, and the caliper slides in and pulls the outer one against the rotor. When you let off, the piston and caliper are pushed back just enough to clear by the wobble of the rotor. There are no springs. If the hardware is in good shape, the piston and caliper both move, but very little. If you do not lube and clean up or replace the hardware when you change pads, the caliper will not slide in as it needs to to pull the outside pad against the rotor. This is a frequent problem causing the inside pad to wear more and uneven braking.
As the pads wear, more and more of the piston stays outside the seal, untouched by the brake fluid. It is protected by a rubber boot, sealing out moisture, grit, salt, etc. Anything that makes it in past the boot can attack the the chrome plated steel piston. The plating is thinned where the it was abraded by the seal. It is slow, but rubber does abrade hard metals. Of course, the seal wears away too. The boot is next to the back side of the pad and heat from it and age harden the rubber and reduce its elasticity. It becomes less and less effective in keeping out yuck, even if it isn’t cracked or torn.
Fresh fluid never touches the boot, the vulnerable part of the piston outside the seal, or the sealing surface of the seal. I doubt if flushing the caliper even disturbs the old fluid in the narrow annular space between the inner part of the piston and the bore. The inlet usually is near the bottom, but the outlet is always at the very top to bleed out the air. I am not even sure flushing the brakes carries any water or grit up and out of the caliper.
In time, the boot lets in enough to corrode the piston, both the plated steel ones and aluminum ones. Pushing the piston back with a lump of rust on it, either makes it stick, or the seal leak. Many times people will install new pads in calipers that were working fine, and then they either leak or stick. The solution is timely, preventative replacement of the old worn rubber parts and fresh lube on the piston. I prefer Sil-Glyde. A caliper kit is cheap, and rebuilding a caliper isn’t that bad of a job. If you let it go too long, the piston is shot, and the cost of a piston and a kit is more than a rebuilt caliper. I have always rebuilt mine in time. After a rebuild or 2, all the original fluid is long gone before it can cause problems. On advantage of rebuilding my own calipers is that I know it goes back together with a good coat of Sil-Glyde on everything, especially the bleed screw, not brake fluid or the special brake greases that are just as hygroscopic.
Cleaning up the caliper and hardware, replacing the old, worn rubber parts, and lubing everything good prevents common problems like sticking or leaking calipers, uneven pad wear, uneven application, and broken bleed screws.
After 5 -10 years, it is good to replace the rubber brake hoses. Master cylinders are up away from the heat, salt, moisture, and grit, and seem to last much longer. If you have salt, it is good to inspect the steel brake lines paying particular attention to places where crud collects, holding moisture and salt against them. Badly pitted ones should be replaced.
In the 3 years I worked in a brake shop, leaking, sticking calipers, uneven wear, broken bleed screws, bad hoses, and brake lines rusted from the outside happened every day. We specialized in trucks. I never remember problems with brake fluid boiling. I never heard of replacing the fluid either.
I have found this thread interesting but confusing. I still don’t know what to do with my car. The dealer calls me at least four times a year telling me I am late for this or that maintenance. The owner’s manual calls for service at specified mileage intervals. But I drive even less than the lady in the OP (after four years, I have not hit 13,000 km (about 8000 miles). About half that is on trips of 4 miles or less, to a supermarket once a week or downtown to a concert every couple weeks. The other half are one RT to New York every year and now there will be one to Boston, so my mileage will increase slightly. Since we have harsh winters, I do have the oil changed before and after the winter season, although it is probably unnecessary. At a local garage. But the service dept of the dealer is really aggressive about telling me how the warranty will be voided. Well, it has less than a year to run anyway.
But I am still confused about when or whether to change things like brake fluid. I do get them to check the anti-freeze level when they put the snow tires on. (Snow tires are completely unnecessary for the kind of driving I do, but they are required by law and I could get a hefty fine for not having them). I used to have a garage I trusted, but it was taken over by some people I don’t know.
Hari,
If you’re this worried, just crack open the owner’s manual.
You’re on the severe service part of the maintenance schedule.
:dubious:
You sound like a real class act. I could barely hear myself think over the sound of you tooting your own horn.
To the OP: Don’t listen to a thing this guy says. There’s plenty of firmly established experts here. Like **Rick **and GreasyJack.
What ? No radiator flush ?
No fuel system flush ?
These guys need a tune up.
One thing on brake fluid changing. I never had a Bosch ABS unit, but I think they may be sensitive to dirt and moisture. I have run Delco units for 10 years only replacing fluid when I changed/rebuilt calipers and wheel cylinders as PM.
If you have Bosch ABS and the manual calls for it, I would do it. I actually would do the bumper flush while still in warranty if the manual called for it.
[Moderator Note]
echo6160, personal remarks like this are out of line for GQ. If you have a contribution to make, address the substance of the post. No warning issued, but don’t do this again.
Colibri
General Questions Moderator
For a vehicle with only 31,800 miles I wouldn’t think any maintenance would be needed except oil/filter changes.
Use your Owners Manual for recommended maintenance. Do not go by the recommendations from the dealer. Dealers are in business to sell service.
My vehicle calls for transmission fluid change and air filter at each 50,000 miles.
Change spark plugs at 100,000 miles. And transmission filter.
After 5 years change engine coolant.
That is all the maintenance required other than engine oil/filter. The manual says change oil/filter when required by the GM Oil Life Monitor indicator or once a year… which ever comes first.
The GM Oil Life Monitor does NOT consider miles driven. It’s a computer program that looks at many things, like engine temperature, oil temperature, RPM, hot starts, cold starts, etc.
The OLM light came on the first time when I had about 8,000 miles. Since then I changed after a year for I still had plenty time on the OLM.
I’ve owned many vehicles over the last 55 years and never had a major problem with any vehicle… always followed the Owners Manual for maintenance.
For the vehicle in the OP, you would be wrong. It’s not the same as your car.
For this car, the factory recommended maintenance at 30K, beyond engine oil and filter replacement and tire rotation, includes:
Engine air filter replacement
Spark plug replacement
A long list of items to inspect, including brakes, steering, suspension, etc.
Also note I said… Use your Owners Manual for recommended maintenance.
If your car is only four years old and only has 8000 miles on it, don’t worry about anything! If by harsh you mean very cold winters then it is a good idea to switch to a low viscosity oil in the winter and back to regular in the spring. You could go with a synthetic oil year-round (i.e. like Mobil-1) but I’m not a big believer in synthetic oil. They’re not a scam like Slick-50, they work as advertised, but they’re way overpriced.
As far as your dealer warranty, I’d read it and see if it specifies both mileage and time intervals. Because as far as car fluids are concerned they can all sit for years undriven without anything bad happening. Except for your gasoline turning to varnish.
:rolleyes:
This is not a true statement, unless you are referring to those fluids sitting in a sealed container on the shelf in the parts store.
Once the container is opened, brake fluid starts absorbing water. No driving necessary.
Oil becomes contaminated (just a bit, but contaminated none the less) the first time you start the engine.
Want me to go on?