So, keep on doing what you "know is right" and be happy.
The problem with trying to discuss technical matter on this Forum is that many people aren't really interested in facts versus "conventional wisdom" and what they have been told by some unspecified person in the past. And, everyone wants you to document your ideas while providing zilch documentation to show why you are wrong (plus being fairly rude in their response).
Published SAE documents contain a wealth of industry information on engineering and testing and I'm sure you collect and read these to keep informed. If a four year old system is corroded it has been exposed to the atmosphere at some time.
A summary of several include (although you know more than Ford or GM):
"Ford does not recommend changing DOT 3 fluid or flushing the system. Ford says their recommendation is a "risk versus benefit" assessment because there's a potential for doing more damage than good. If sediment or contamination from the master cylinder is pushed through the ABS unit, it can cause big problems. Flushing the system also increases the risk of air entrapment and leaks.
Ford says their brake systems are engineered to tolerate brake fluid contamination of up to 3 percent moisture without fluid boil (which is close to the saturation point for DOT 3 brake fluid). Ford said they measured the water content in 7 to 10 year old Ford vehicles and found that the water content was actually quite low: only 1 to 1-1/2 percent. So based on their findings and the design target of 3 percent water, they see no need to change the fluid for preventive maintenance. Most of the water in a brake system is introduced when the sealed system is opened during unnecessary maintenance"
"GM's position on brake fluid is that they do not recommend changing it on most vehicles. GM brake systems are sealed and should not need flushing. GM's goal is to reduce maintenance requirements, not add them."
Ah, I see you can selectively quote info from the aa1car.com website. The article that you quoted from is from 2001, and many manufacturers have changed their stance on brake fluid service since then. In fact, if you go the the same article a year later, you get the following:
GM says fluid changes are unnecessary - except for some offshore models that do have a specified change interval. For 2004, new GTO Monaro (Holden) from Australia will have a fluid change recommendation. GM is, however, currently reviewing the FASCAR drip strip method of checking brake fluid.
In the GM quote that you provided, you left out "The only exceptions are Metro and Tracker models". So that's at least a couple of GM models that have fluid change intervals. IRIC the FASCAR test strips are now accepted by GM for fluid testing.
Ford says need to flush and change fluid varies depending on the area of the country (no moisture problem in Arizona but there is in Florida), and also on the robustness (corrosion resistance) of the parts in the brake system. Ford's service life for brake fluid is 10 years, 150,000 miles (has been this for past four or five years). Ford says if there is a reliable way to test fluid and the fluid tests bad, then it should be changed. Otherwise, leave it alone.
That was 2002, and manufacturers have changed info again. As I stated in my last post, Ford now recommends a service interval of 3yrs/36,000 miles. Most imports, asian and domestic, have reccomended service intervals of 2-3 years, or mileage intervals that put them in the same ballpark. Not sure why domestic makes don't have recommended intervals, though brake fluid is on a "periodic" or "as needed" basis, probably to make service intervals look longer.
Over on iATN,
one post states:
If you want to sell brake fluid changes and stay out of
trouble, use the strip dip test strips to test for copper
contamniation and a refractometer to test for water. Having
proven, accepted test results that show its bad allow you to
responsibly sell the fluid change. An interesting note, I
worked on the tech line for Bendix for 8 yrs, we tracked
hydraulic complaints by vehicle make and then separated them
by manufacturers that recommend fluid changes and those who
say it lasts forever. Over 2000 hyd complaints, 1890 of them
where attributed to automakers who say fluid lasts forever!
A hint, test fluid removed from the caliper, not the
resivour.
The biggest reason for a brake fluid change or "flush" is a PH shift that can have an end result of internal corrosion in the brake system because the fluid becomes acidic. The easiest way to test for contamination are test strips that test for the presence of copper, or a refractometer to check for water.
I wouldn't change fluid just to change it, but I make damn sure that it is up to accepted standards by checking for contamination. Generally I see signs of contamination within two years of the last time the fluid was changed, and if it's at all questionable, I change it. It's not for the safety of the other idiots on the road, it's for the safety of the driver.
As a side note, I am a mechanic, though I don't make money working flat-rate. I work for a municipal fleet shop, and am paid by the hour, so I have no stake in "selling" fluid flushes, my only interest is in doing the job right.
, you seriously need to lay off the "pipe" for a while...
