vwdsmguy
Veteran Member
That says it----
The correct term is hygroscopic. It absorbs moisture so that it can't condense on the surface of the hard lines and corrode sufficiently to perforate or otherwise cause the line to fail.... Brake fluid is hydrostatic ...
That would be "By the Book"IMHO every 2 years irrespective of mileage.
Overkill? Maybe. But I've never had to replace a caliper in a vehicle where that's been done on a religious, every 2-year basis and brake fluid is cheap -- some vehicles now approaching drinking age.
You decide.
It is quite interesting to see how different manufacturers view the need for brake fluid replacement differently - when I owned a 2010 Jetta TDI, the maintenance schedule did call for a brake fluid replacement every 2 years. Last July, I returned my Jetta to VW and bought a new Toyota 4Runner. The first thing I did after bringing the new vehicle home was to check the maintenance schedule and, lo and behold - no scheduled brake fluid replacements. Ever. The only thing the owner is supposed to do is to check the level of all fluids every 5,000 miles and, if needed, top them off. This makes me wonder whether Toyota knows something VW does not. And maybe it's the other way around.
I owned the Jetta for almost 9 years, but I never bothered to replace the brake fluid. Yes, brake fluid is hydroscopic, that is a known fact. However, there is only very limited volume of air above the fluid in the reservoir, and that air is sealed off from the outside atmosphere by a rubber gasket. So, the only air the fluid comes into contact with is that very small volume between the fluid and the gasket. That was pretty much my rationale for not changing the fluid even though the maintenance schedule said I should. But since all fluids deteriorate over time, I was planning on changing it eventually, possibly after 10 to 15 years. For the same reason, I plan on changing the transmission fluid in the 4Runner at 50,000 mile intervals, although Toyota claims this to be a "lifetime" fluid if you don't do much towing. I tried to purchase a shop manual for the vehicle when I was taking delivery so that I could do this type of maintenance myself, but the salesman told me Toyota no longer offers them. When changing the transmission fluid on the 4Runner, what is the scan tool used for and how is the procedure performed? When the time comes for the fluid to be replaced, my plan was to drain the old fluid, measure the exact volume that drained and replace it with the exact same amount of fresh fluid.I work for toyota and we've gotten away from making customers spend money on maintenance. Since they introduced Toyota care people just want everything for free. The only fluids left with service time is coolant and trans fluid. You need our scan tool to check the trans fluid btw if you didn't know it's an overflow style pan on the 4Runner. The 4runner is one of the last good products we sell.
Toyota (and the others) know you'll get out of warranty before the calipers (or worse, the master and ABS pump!) are damaged by corrosion due to moisture being absorbed by the brake fluid if you never change it. Thus it is not on the "maintenance schedule" since it will not cost them money (it'll cost you instead!)It is quite interesting to see how different manufacturers view the need for brake fluid replacement differently - when I owned a 2010 Jetta TDI, the maintenance schedule did call for a brake fluid replacement every 2 years. Last July, I returned my Jetta to VW and bought a new Toyota 4Runner. The first thing I did after bringing the new vehicle home was to check the maintenance schedule and, lo and behold - no scheduled brake fluid replacements. Ever. The only thing the owner is supposed to do is to check the level of all fluids every 5,000 miles and, if needed, top them off. This makes me wonder whether Toyota knows something VW does not. And maybe it's the other way around.
There are many components and systems in the 4Runner that require servicing both during and past the warranty period, yet they are mentioned in the maintenance schedule (the schedule stops at 120,000 miles). Toyota could have put the first brake fluid replacement at 3/36 and every 2 years thereafter in order to avoid paying for this service item, but they didn't. Also, if not changing the brake fluid causes serious corrosion of the metal components that are in contact with the fluid, reasonable person would assume that, due to the low cost of the fluid and how quickly the procedure can be completed, this is not a cost issue, but rather a safety issue, and that it would be addressed by Toyota in the maintenance schedule. Toyota's design team instead chose not to require periodic replacements of the fluid, and I am pretty sure Toyota's lawyers had the final say in this matter, being fully appraised of potential consequences of a ruptured brake line.Toyota (and the others) know you'll get out of warranty before the calipers (or worse, the master and ABS pump!) are damaged by corrosion due to moisture being absorbed by the brake fluid if you never change it. Thus it is not on the "maintenance schedule" since it will not cost them money (it'll cost you instead!)
Brake fluid is hygroscopic and everything in a brake system operates on pretty tight tolerances. Corrosion either makes things in the system stick or leak and thus require replacement. If you've had a failed caliper apart that has not had the fluid changed regularly it's pretty obvious what happened to it and why it failed. The system is NOT "sealed"; it can't be because as the pads wear the level in the reservoir must fall somewhat (the pistons are further out in their bores.) The cap on the master does slow the exchange of air in that space but cannot prevent it entirely.
A can of brake fluid is a few dollars and with a pressure bleeder it takes under 30 minutes to flush and change the fluid. Done correctly no air gets into the system and thus you don't need to purge the ABS pump either. Not doing it every two years means you'll get to buy brake components; doing it every two years means the OE brake components will likely last the lifetime of the vehicle.
You choose.