n8kwx wrote:Why is the brake fluid rated for 30k miles / 24 months???
This seems like a much more intensive schedule than most cars.
$$ Perhaps. Never replaced brake fluid that soon.
Every two years is a very reasonable interval for brake fluid replacement. Many experts have long recommended changing the brake fluid every year or two for preventative maintenance. Their rationale is based on the fact that glycol-based brake fluid starts to absorb moisture from the moment it is put in the system. The problem is obviously worse in wet climates where humidity is high. After only a year of service, the brake fluid in the average vehicle may contain as much as two percent water. After 18 months, the level of contamination can be as high as three percent. And after several years of service, it is not unusual to find brake fluid that contains as much as seven to eight percent water. Water contamination increases the danger of brake failure because vapor bubbles can form if the fluid gets too hot. Three percent water will lower the boiling point as much as 50%. Vapor displaces fluid and is compressible, so when the brakes are applied the pedal may go all the way to the floor without slowing the vehicle. Anyone who has done "spirited" performance driving and experienced this "brake fade" will agree that the relatively small expense of flushing the brake fluid is well worth it.
In addition to the safety issue, water-laden brake fluid promotes corrosion and pitting in caliper pistons and bores, wheel cylinders, master cylinders, steel brake lines and ABS modulators.
Only General Motors and Chrysler do not mention brake fluid in their scheduled maintenance recommendations. In Europe, brake fluid changes are often recommended. BMW says the fluid should be changed every two years. Honda recommends a flush & fill every 25,000 to 30,000 miles. Subaru also recommends a 30,000 mile brake fluid change. Volkswagen recommends changing the fluid every two years, and clearly states this in their owners manuals, as does Porsche.
I change mine every year, as I live 3 blocks from the ocean, and high humidity from fog is common. It is a simple procedure and can be done in an hour for a cost of $10-12 (the cost of a liter of Dot4 fluid) if you don't mind working on your own cars.
La Jolla, CA
2011 SLe #1317 del. 4/1/11
1st bar lost at 31,953 miles
2nd bar lost at 38,685 miles
3rd bar lost at 50,711 miles
4th bar lost at 59,758 miles after 64 months
Battery replaced at 61,307 miles.