BMW X3 Service & Repair Manual: General information on automatic transmission fluids

1.0 GENERAL INFORMATION ON AUTOMATIC TRANSMISSION FLUIDS

Automatic Transmission Fluid was developed especially for automatic transmissions. It requires additives which are carefully matched with each other, a high viscosity index and a solidification point below -40 ºF/-40ºC.

Friction behavior of Automatic Transmission Fluid in plate-type clutches under very different operating conditions is extremely important. Other important factors are:

• Wear protection
• Oil film shear resistance
• Adhesive property
• Oxidation resistance
• Corrosion inhibition
• Sludge prevention
• Temperature-dependent viscosity changes
• Compatibility with sealing materials.

2.0 OIL ADDITIVES

Automatic transmissions are designed so that oil additives are not necessary. BMW disapproves the use of any oil additives and cannot accept the liability for any consequential damage which results from using oil additives.