Checking the oil level in transmission units (Audi 100 C4)

Checking the gearbox for leaks

In the gearbox, oil is not consumed as in the engine, but can leak out in loose bridges. If the gearbox housing is not visible in the engine, but can leak out in loose bridges. If the gearbox housing is not visible









Support the car in a horizontal position.



Remove the 17mm Allen screw.

If some oil leaks out, the level is normal.

Otherwise, insert your index finger into the hole and check if the oil level reaches the hole. If yes, then the level is OK.

If there is not enough oil, the workshop should top up with the specified type of oil to the required level.

Note: It is not recommended to pour oil yourself using a funnel and a long hose due to its high viscosity.

Choosing the Right Oil (transmission fluid)

Transmission fluid is poured into the gearbox for long-term operation. Metal particles are collected using a magnet.

Audi recommends using the following types of transmission fluid:

• Gearboxes - only synthetic oil of viscosity grade SAE75 W-90.

Checking the ATF transmission fluid level in an automatic transmission

The automatic transmission is filled with synthetic ATF fluid (Automatic Transmission Fluid). It serves as a lubricant and to regulate the pressure in the gearbox. ATF fluid should be marked Dexron and then a number. Using the wrong type of fluid can cause gearbox malfunctions.

To check, the ATF fluid must be warmed up to the warmth of your hand, for this you should drive for five to ten minutes. The volume of the fluid changes depending on the temperature. When cold, the level is lower, after a long drive - higher.

Apply the handbrake, move the selector lever to position "P", and start the engine at idle speed.

The dipstick is located on the engine at the rear left in the direction of travel and is equipped with a plastic flag, it should be wiped with a clean, thread-free cloth.



Insert the dipstick and pull it out again. The amount of liquid between the upper and lower marks is 0.66 l for a dipstick with a plastic flag and 0.23 l for a dipstick without a flag.

The level should be between the marks. The lower mark of the dipstick without a flag is used to fill in new fluid when replacing it.

Until mid-1985, ATF fluid was produced in pink and transparent colors. Later, dark brown fluid was produced.

If liquid (no matter what brand) it smells burnt, which means it's spoiled.

If the fluid level is low, you should not only top it up, but also check the gearbox for leaks. If there is a leak, contact a workshop.

If the fluid level is too high, it may indicate damage to the gasket between the planetary gear and the final drive.

Check the fluid level in the final drive.

If there is too little fluid, you should contact a workshop for repair and replacement of the fluid.

If the level in the main gear is normal, excess fluid from the gearbox should be drained, as this may cause damage to the gearbox.

Main gear on automatic transmission

The final drive of an automatic transmission uses a different type of fluid than the manual transmission. It must have a viscosity of SAE 9 and be designated API GL5 or MIL-L-2105B.

Checking the level is necessary in the following cases:

• If the main gear housing is contaminated on the outside with transmission fluid.
• If the fluid level in the automatic transmission has dropped or risen, and leaks are not visible from the outside. In this case, there may be an exchange of fluid between the planetary gear and the main gear, as described above.

Transmission fluid replacement

Under normal operation, the transmission fluid should be replaced every 45,000 km. If the vehicle was driven mainly on short trips or in poor road conditions, the transmission fluid should be replaced after 3,000 km. To do this, drain the old fluid and clean the oil pan and mesh filter at the same time (in the workshop).

Checking the fluid level in a neutral hydraulic device

Vehicles with power steering and/or adjustable ride height are equipped with a central hydraulic unit. Hydraulic fluid level (type AOE 041 0201 or Aral 1010) it is checked in a transparent tank at the rear of the engine compartment.

To check the fluid level, start the car at idle speed.

Cars without adjustable ground clearance are equipped with a cylindrical expansion tank. When the cap is removed, the float of the fluid level control device is visible. The fluid level should be between two marks. When topping up, add fluid up to the "Max" mark.



Vehicles with adjustable ride height are equipped with a larger expansion tank, which has two pairs of marks for unladen and fully laden vehicle.

If the car is empty, the fluid level should be between the two upper marks. If it is fully loaded, between the two lower marks.





When topping up, add fluid up to the "Max" mark. Usually, a lack of fluid indicates a leak in the system. In this case, you should not just top up the fluid, but first find the leak points.