How often should you Change your Brake Fluid
The general opinion of those in the motor trade, is that brake fluid should be completely changed every two to three years. This is because the brake fluid in your car not only chemically interacts with the rubber seals and metal pipes, but the fluid also draws in moisture. All of this lessens the effectiveness of your brakes, as the fluid slowly breaks down.
Because brake fluid is hygroscopic, it draws water in through the seals around the pistons, and that tiny hole in the cap of the master cylinder. This contamination is gradual, but persistent, and goes totally unnoticed until it's too late. Now I know that there are people out there who have used the same brake fluid for years without any problems. Ask yourself this though, should you take the chance that your brakes will be fine, when a couple of hours work and pint of brake fluid can guarantee it.
Every time you use your brakes, the components heat up quite dramatically. Your brake fluid is designed to deal with this heat, but the moisture within the contaminated fluid isn't. The water boils, and releases a gas into the brake pipe behind the pistons. Because this gas can be compressed easier than the brake fluid, the brake pedal will seem to operate as usual, but you won't be able to stop your car.
The water reaching boiling point can also cause the flexible brake pipes to expand, and further reduce your car's braking ability. It really doesn't take much moisture in the fluid to effect the braking of your car. You also shouldn't confuse brake fade with that spongy brake pedal feeling you get from badly maintained brakes.
You can regularly check your brakes, and have everything tip-top, but if your fluid is on its last legs, you're still taking a big chance. If you are in the habit of braking heavily at the last minute, you are dramatically increasing the chances of experiencing brake fade. Just plan your braking a bit better, and use your gears to help slow you down. A car is no good if you can't stop when you need to.
So what is the best way to go about changing your brake fluid? It's not a hard job, and with the right tools, you can do it yourself. There are a couple of kits you can purchase, to make life easier. The first kit eliminates the danger of the master brake reservoir running dry. The second kit is a one-way valve on the end of a tube, that stops air being sucked back through the opened bleed nipple.
Before you bleed each wheel, empty the reservoir as much as you can. I use an old turkey baster to suck up the fluid; it's cheap and very effective. Refill the master brake reservoir with new fluid, and now you can bleed each calliper in turn. Never let the reservoir go dry, or you'll give yourself double the work bleeding the system again. Once the old fluid is out, and there is no air in the system, tighten everything up.
Make sure the brake pedal operates correctly and that all four brakes are effective. That is all there is to it, a couple of hours work at most, that could save your life. So next time you replace your brake pads, consider whether it's time the fluid was replaced too.
