Transmission Fluid (Oil)
The automatic transmission provides pressure regulated hydraulic fluid which is filtered for all of the transmissions functional requirements. All BMW automatic transmissions are designed to operate with specific fluids. Use of non-approved oil will cause malfunctions and irreparable transmission damage which is not covered by BMW warranty.
The transmission fluid provides the following functions
- Lubricates mechanical components (planetary gears, bearings etc.).
- Removes heat and transfers heat to transmission cooling system. (Heat Exchanger).
- Removes debris and contaminants to sump and filter when circulated.
- Provides a transfer of kinetic energy in the torque converter.
- Allows hydraulic operation of mechanical components (clutches, brakes) via control of the valve body.
Also, transmission fluid has various properties to prevent oxidation and breakdown from heat and friction. Each type of transmission fluid has properties specific for each transmission application.
Fluid level is crucial in the proper operation of an automatic transmission. Improper fluid levels will cause improper operation and eventually irreparable transmission damage. Improper fluid level can cause
Scheme 243
- A low fluid level can cause an interruption in oil flow during fast acceleration or hard braking which can cause gear shift malfunctions.
- An excessively high fluid level can cause the rotating mechanical components to paddle in the oil. This produces foam which introduces air into the hydraulic system.
- A low fluid level can also cause transmission overheating causing premature transmission failure.
Transmission Fluid Application
There are numerous types of transmission fluid used in BMW transmissions. With the exception of the early transmissions (4HP22/24, A4S310/270R and the A5S310Z) all current BMW transmissions use "Lifetime Fill" transmission fluid. There is no maintenance required for these transmissions. It is important to use the correct fluid. Incorrect use of the transmission fluid can cause non-warrantable transmission damage.
When performing repairs on transmissions with lifetime fluid, it is important to drain the transmission fluid in to a clean container for re-use. New fluid should only be used for transmission replacement and for topping off after repairs.
Also, transmission fluid level is vital to the proper operation of the transmission.
| Transmission | Fluid Type | BMW Part # | Container | SIB Ref. |
|---|---|---|---|---|
| 4HP22 4HP24 | Dexron III Mercon | Available Commercially (Castrol or Texaco) | N/A | |
| A5S310Z 530i/iT (E34) | Dexron III | Available Commercially (Castrol or Texaco) | N/A | |
| M3 (E36) | ESSO LT 71141 | 83 22 9 407 807 | 20 liter container | B 24 03 95 |
| A5S325Z | ESSO LT 71141 | 83 22 9 407 807 | 20 liter contalner | |
| A5S440Z | ESSO LT 71141 | 83 22 9 407 807 | 20 liter contalner | |
| A5S560Z 740 (E32), 540 (E34) 840Ci (E31- 6/93-12/94) 740i/iL-750iL (E38) | Shell LA2634 | 83 22 9 407 765 | 5 liter contalner | B 24 11 92 |
| 540i (3/96-12/96) 850Ci (10/94-6/97) | ESSO LT 71141 | 83 22 9 407 807 | 20 liter contalner | B 24 02 94 |
| A4S310R A4S270R (THM-R1) | Dexron III Mercon | Available Commercially (Castrol or Texaco) | N/A | |
| A5S360R A5S390R | Texaco ETL 7045E Texaco ETL 8072B | 83 22 0 026 922 83 22 0 024 359 | 25 liter contalner 25 liter contalner | |
| GA6HP26Z | Shell M1375.4 | 83 22 0 142 516 |
BMW AUTOMATIC TRANSMISSIONS FLUID SPECIFICATIONS