Next to the engine, the automatic transmission is the most costly and complex mechanical component of your vehicle. What’s more, automatic transmission fluid is called on to serve many functions. It operates hydraulic components, smoothes the transmission of power, provides lubrication, keeps seals soft, protects internal parts and acts as a coolant.

To preserve these capabilities, the automatic transmission fluid should be serviced at the intervals specified by the vehicle manufacturer in your owner’s manual.

Modern automatic transmission fluid is a carefully formulated chemical compound, often created with a specific transmission design in mind. While a number of companies market “universal” transmission fluids, many vehicle manufacturers specify unique and proprietary fluids for use in their automatic transmissions. Not using these fluids can affect shift quality and transmission life.

Sierra Car Care recommends that motorists consult their owner’s manual and make sure any fluid used in servicing meets the requirements of the vehicle manufacturer.

Checking Automatic Transmission Fluid
The automatic transmission fluid level should be checked with the transmission at full operating temperature and the engine idling. Typically, at least 15 minutes of operation are required to fully warm up the transmission. NOTE: Some newer vehicles have sealed transmissions without a dipstick.

  • Park the vehicle on a level surface, apply the emergency brake and place the transmission in park or neutral (check your owner’s manual to determine which).
  • Open the hood, then locate and remove the transmission dipstick, making sure to avoid any hot or moving engine parts.
  • Wipe the end of the dipstick clean with a rag, and note the level markings. Some dipsticks have one mark for FULL and another for ADD. Other dipsticks may simply have small holes indicating the maximum and minimum oil levels, still others may have a cross-hatch area indicating the acceptable range.
  • Insert the dipstick fully back into its tube, then remove it immediately and read the level.
  • If the fluid level is at or below the ADD mark, then add enough fluid to bring the level up to the FULL mark. Do not overfill. Typically, the distance between the ADD and FULL marks is equal to one pint of fluid. New automatic transmission fluid has a red or pink tint. Fluid that is red dish-amber to medium brown has been in service for some time, but a minor color change of this type is considered normal and is not cause for fluid replacement. However, fluid that is dark brown or black does indicate a lack of maintenance and should be changed as soon as possible. Milky pink or brown fluid, or burnt-smelling fluid of any color, indicates major problems that should be checked out by a transmission expert as soon as possible.

Note: These instructions are intended as general guidelines. Please consult your owner’s or service manual for specific instructions on changing the oil and filter on your vehicle. Use extreme caution when lifting or jacking any vehicle.