Fluids will always break down over time from wear and tear, miniscule debris from parts and from heat. All fluids in your vehicle will eventually need to be serviced. Fluid maintenance is probably the single most important repair for getting your money's worth out of your car. My trusty old Corolla had over 345,000 miles when I sold it. The transmission fluid was still a beautiful red color and worked perfect, because at every oil change, I would drain 2 quarts out and refill it.
I always get a kick out of the car manufactures selling point “life time fluid”, it does not need to be changed. I still have yet to see a fluid that does not break down over time. Take a BMWs transmission, filled with BMWs signature lifetime fluid, do you want to know how many BMW transmissions I have seen fail? When I am asked about BMW’s lifetime fluid, my favorite line is, “Yes, that fluid will last as long as your transmission will. The question is, how long do you want your transmission to last?”
The same goes for brake fluid. It will absorb moisture over time, and living here in the beautiful Pacific Northwest, we do see our fair share of wetness. In Washington, we don’t rot, we rust. We know that moisture will eventually lead to rust or corrosion and with all the moving parts in a brake system, that usually will not end well. Simple fluid maintenance will help prevent component failure over time.
I look back to cars 50-60 years ago and no one ever changed the fluids. Then I also realize that the components in the vehicles never lasted that long and required servicing, which usually ended up with requiring new fluid. The other aspect, is that the systems on today's cars are built with tight tolerances, precision and advanced technology that was not used in automobiles back then. My 1930 Ford Model A does not even use an oil filter. Could you imagine trying to run an engine today without an oil filter?
Remember, simple fluid maintenance could be the difference between replacing parts at 100,000 miles or 200,000 miles or longer, as in the case of my Corolla. I am a firm believer in servicing fluids. We see cars every day, and can see that the vehicles that are serviced have less breakdowns and last longer. Whereas the cars that are just driven, will eventually leave you stranded and require a large repair bill and possibly a donation to the local towing company. Which as Murphy's law states, will happen at the most inconvenient time.