2007 Toyota Camry - Brake Fluid Flush Required?

Not sure I’d agree with that article. Moisture content is easy to measure with a $35 tester. PPM copper is not. Maybe Firestone knows this and has adjusted their sales pitch accordingly?

Our Audi A4 has a required brake fluid flush interval of 2 years, regardless of mileage in Audi’s maintenance schedule. My tester shows 4% moisture in the fluid right now after I did a partial flush 15 months ago so I am due for a full flush based on that alone. I don’t have the tools to do analysis of copper content so I have no idea what the PPM of copper in the fluid is. I’d bet it is lower than 200 PPM.

The Audi seems to collect moisture faster than my GM truck. Now, I do live where the humidity is high year 'round, so I’ll continue to use % moisture as my indicator.

How accurate is your moisture tester? Low levels of moisture are about the same level of accuracy for expensive instruments used for measuring moisture levels of fluids and gasses. I’m thinking specifically of dew point measuring devices, themost accurate device family.

I can’t find any data for my (turns out it was $7!!) tester. So I don’t know the claimed accuracy. It has 2 prongs that must use the electrical properties of wet DOT 4 to determine moisture content. The tester is specifically for DOT 4. Values for DOT 3 must be somewhat different.

It has 5 LED’s registering 0 to 4%. If I test DOT 4 fluid fresh out of a sealed container, it correctly registers 0%. Beyond that, I am trusting the device only to tell me if the moisture content is fresh at zero %, a little 1-2% or a lot, 3-4%. So I am assuming no better than 2% accuracy.

For my street cars, they get changed if I see 3 or 4%, which I believe would be a fail in Europe as well. For my track Mustang, if I see anything but 0% or 1%, it gets changed.

once fuid has water in it, it would become conductive, so testing with multimeter on the highest (megaohms) range would show infinity in a new fluid and something lesser in a contaminated/old one

apparently, it is also direct galvanic effect what can be tested:

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I worked in the aerospace industry for several years and totally bought the concept of preventative maintenance; deferring part maintenance until after part failure is not acceptable to me if it can at all be avoided.


Very true, but we are dealing with cars and not aircraft or the space shuttle. Cars have a different purpose and lifespan for every owner out there and there is a very different cost/benefit analysis for every driver. I read a study that showed there was no statistical difference in transmission failures between those that were serviced every 30,000 miles and those that had no service up to 140,000 miles. If I’m the kind of driver that expects a useful life of 150,000 miles out of my car, I see no reason to service my transmission.

On the other hand, I recommend replacing batteries that are over 6 years old regardless of whether they test good or not. Some people here say wait until you notice an issue starting the car. The goal may be having a car that always starts or the goal may be getting every last nickel out of your battery.

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Full of air and NOT brake fluid. It needed massive bleeding to get the air out indicating the caliper had never been bleed from the factory installation.

During NYC’s financial crisis of the late '70s-early '80s, Mayor Koch instituted “deferred maintenance” for the city’s subways and buses. Maintenance was deferred until the point of total failure, necessitating very high repair costs. In addition to the cost of those repairs, the “cost” for the public–in terms of their safety/convenience/quality of life–was staggering.

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It’s no wonder the brakes felt better than ever after finally being able to bleed the air out, the way it was would have been the equivalent of having no front right brake at all. Stepping on the brake would make the vehicle pivot on the left tire.

It’s surprising you didn’t return the vehicle for service the same day you took it home.

Left rear would be just as bad, since air in the caliper would affect the whole circuit.
Assuming it’s a dual-diagonal system.

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I am truly thankful maintaining a car is much less expensive than maintaining an aircraft; this is where common sense must prevail accompanied by some careful research into the particular car being maintained. For example it may be a false economy to defer maintenance on an interference engine that uses a rubber timing belt.

Do you happen to recall how the participants were selected?
I can imagine that owner getting 120K miles from the car in 4 years (my coworker does just that) and another owner getting 120K over 12 years have a very different wear pattern.

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I discovered decades ago it is very much less expensive to have friends and relatives with boats and aircraft than to feed your own.


The cars were all BMW and I do remember that the study was done within a specific time period so I imagine driving habits were similar. I can’t remember much else nor can I locate the details anymore.

However, 30+ years in the business seem to back that up. I don’t see many transmission failures (a few specific models aside) before 120-140K. So if I’m the kind of guy that trades off his car every 10 years or so, I would see no benefit to maintaining the transmission for the next guy.

For some people it’s not just about the money. Batteries are cheap. Yet there are people who post on this board who drive with an aging battery and keep a jumper pack in the trunk for when the battery fails, saying “there are worse things than needing a jump start.”

And there are also people for whom car maintenance is something for the second owner to do. I was at a seminar, and one of the trainers explained that she had neither the time nor the inclination to wonder about what kind of tires to buy, when to replace the brakes, or where to take the car for a 90K service. She avoided all that by leasing a car every 3 years.

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For reasons I don’t understand, I have a respect for things mechanical and a desire to see it operate as designed; I have no idea why I care but I do.


I’ve never owned either boats or aircraft’s; as luck would have it, I served in the USN and later worked for LTV. This experience adequately demonstrated the cost of maintenance for both modes of transportation and left me with no desire to experience that on a personal level.:slightly_smiling_face:

When stuff breaks in an aircraft, it can very easily stop flying. We can all appreciate how bad that can be if you are in the middle of an airplane trip.

If a car stops running it can be annoying to life threatening, depending on when and where it happens. For most drivers, that means you don’t get to work or delay returning home. For long distance travelers, breaking down driving across Death Valley could have very serious consequences.

Certain deferred repairs could be seriously life threatening, like a cracked wheel, broken wheel studs or failing wheel bearings. Upside down in a car will not be pretty, even if you walk away. A broken timing belt, not so much drama. Well, at least physical drama. The verbal drama might get a bit active.

I’ve been stuck a couple of times in the boonies (pre-cell phones) wondering how I was going to resolve the problem. One car was a brand new company owned car, the other mine. Both times a tow truck just happened along to bail me out (very good luck!!). Neither case could have been prevented by preventive maintenance, but that doesn’t stop me from being a bit OCD about it!

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That’s understandable.
I’m also on the same 10yrs treadmill, but I do like to have the option to keep car longer if I wish, although it never happens.

Recently I had to deal with getting two cars for my kids and my bet on keeping our Nissans for that did not work out due to CVT failures, even with me doing preventative fluid changes.

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The consequences of a broken timing belt depends on whether it is in an interference or a non-interference engine; my 3.0 L Honda V6 just happens to be one of the only two non-interference engines in the Honda lineup that uses a timing belt. Most of our driving is local and never far from help; in spite of that we still have AAA.