Whenever it shows signs of defect, damage, or leakage. It might last for the life of the vehicle, or it might not.
You add it to the master cylinder mounted on the firewall, drivers side. Do not overfill, and only add fluid from a sealed container. Use the proper fluid as listed on the master cylinder cap. If it is low of fluid it means that you either have a leak or the brake pads have worn down, and they should be checked. You may need to have your pads replaced. Fluid does not evaporate and those are the only reasons it will be low. This car is 16 years old, and if you have not had the fluid changed it is way over due. Have the entire brake system flushed and fresh fluid installed. Brake fluid should be changed at least every 3/36. This is an often overlooked service.
That depends on where it's leaking out; if it's at the master cylinder, you have a bad master cylinder, if it's at the wheel cylinder you have a bad wheel cylinder if it's at a caliper... well, you get the idea. If you know how to repair a master cylinder, wheel cylinder or caliper, you can often get by with a little savings but it's usually best to just trot down to your local auto parts retailer and get a new or rebuilt one.
Usually that means that you have a failed master cylinder and it's sucking air. Often you can see the booster soaked with brake fluid. If the master cylinder ran dry at all, it has to be bled seperately.
If there is fluid leaking in or on the wheels, your problem is most likely there at the leak. When the fluid fails to reach the wheels is when the master cylinder would be in question. Most often if you find and repair the leak, you have fixed the problem. After fixing the leak,make sure you fill your fluid to the full mark after you bleed the brakes to prevent any air from corrupting the system.
When its old
The simple answer is, never. Both of these fluids only nedd replacment when other service is done. Ie: master cylinder replacment.
Automatic transmission fluid should be changed according to the manufacturer's suggestions. Many manufacturers suggest having the fluid changed at every 100,000 miles.
It depends on the type of fluid and level of contamination or heat. if there is no problem with the fluid it should be left alone!
Every 5000 miles.
If it's leaking out the end of the master cylinder you'll need to replace it. Don't even bother trying to rebuild the clutch master cylinder, it just isn't worth the trouble. You can buy one from most auto parts retailers for about the same price as a rebuild kit, and often for less.
MAKE SURE THE MASTER CYLINDER IS LEVEL...THEN REMOVE THE TWO SCREWS ON TOP ... PLACE A HOSE OVER THE TOP OF THE BLEEDER SCREW NEAR THE SLAVE CYLINDER. PUMP THE LEVER A FEW TIMES AND HOLD LEVER IN. LOSEN BLEEDER SCREW MOMEMTARILY THEN TIGHTEN... REPEAT PROCESS UNTIL YOU ARE SATISFIED WHITH RESULTS.. BESURE NOT TO LET THE MASTER CYLINDER RUN TO LOW ON FLUID OR YOU WILL HAVE TO REPEAT ENTIRE PROCESS. you might also want to inspect the cluth slave cylinder, or have your mechanic do it. often it will fill with dirt and hydralic fluid and physically blick the hydralic cluth assemble from moving back and fourth.
You've lost all pressure on the clutch cylinder. I can't tell you if it is the master cylinder, or the slave cylinder, or just that you have a slow leak and ran too low on fluid without being there to see it. Check the fluid level, if it's low or out refill it, then pump the clutch by hand in and out and check to see if the fluid is running out anywhere, the hose between the two cylinders may also be damaged, but you'll have to find that leak to be sure. If no leaks are found then it is probably a slow leak, you can bleed the system and get by for a little while but replacing the leaking part will need to happen soon, it is most likely the slave cylinder though, they go bad much more often than the master cylinders.