About Clutch Fluid

Anyone who owns a vehicle with a manual transmission knows how important maintaining the clutch fluid is. Without it, manual transmission clutches will cease to work properly, or in some cases, can cease to work at all.

Identification

Some people think that clutch fluid is a type of fluid all its own, like anti-freeze or oil. The truth of the matter is that clutch fluid is nothing more than a DOT 3 or DOT 4 level of brake fluid.
Brake fluid is broken up into DOT categories, ranging from 2 to 5. The higher the number, the more heat tolerance the fluid has and the higher the boiling point, as well.

Function

Older manual transmission vehicles used to have a cable that connected the clutch throw out fork to the brake pedal. Therefore, the use of clutch fluid was unnecessary. Today, however, that old cable system has been replaced with a hydraulic system. This system is comprised of a master cylinder that is attached to the clutch pedal. This cylinder has fluid in it. When the pedal is pressed down, the fluid becomes pressurized.
When pressurization happens, the fluid then moves the slave cylinder, which is housed near the transmission bell. Once this process is complete, the clutch is disengaged.

Significance

Because most modern clutch systems work off of the hydraulic system, it's necessary to keep the fluid level in the reservoir topped off. If the clutch fluid level falls below what it is supposed to be, you may begin experiencing hard clutching. This means that your clutch may either get stuck when you press it in, or it may not be easy to press in at all.
Usually filling the clutch fluid can correct these problems.

Misconceptions

When choosing a clutch fluid, remember that all you need is type DOT 3 or DOT 4. Type DOT 5 is usually only used in race cars or high performance sports cars because the brakes typically see heavy usage and are prone to getting hot.
Hydraulic clutches do not generate heat like braking systems, to brake fluid with a high DOT number is not necessary.

Considerations

Not all clutch problems are a result of low clutch fluid. If you have checked the fluid reservoir and see that it does not need to be filled, or if you have filled the reservoir and are still experiencing problems with your clutch, take your vehicle to a certified mechanic to get checked. There may be a more serious problem causing your clutch to malfunction.
Clutch replacement can be costly, so make sure to keep the clutch fluid topped off.