Several times a month, folks come in thinking they need an automatic transmission rebuild. Sometimes they do and many times they do not. When asked why they felt the automatic transmission needed rebuilding, they answer, "I was told the fluid was dark."

Automatic transmission fluid color, along with other symptoms, can be an indication of an automatic transmission problem. Fluid color is NOT by itself a reliable indicator. Darkening of fluid with age is a normal characteristic. Knowing normal color and other symptoms to look for can keep you from being taken advantage of.

New automatic transmission fluid will have a bright red, translucent color. The red color is the result of dye that is added to the fluid for identification. It is NOT an indication of the quality of the fluid nor the condition. An automatic transmission can have a significant amount of wear and still have clean red fluid.  It can also have dark fluid and still be okay.  While every transmission will benefit from a proper service, fluid color alone is not an indication of a problem.  Many of the newer fluids on the market today are also significantly darker than fluid of the past, even when new.

As fluid ages, it tends to get darker and more brown in color. This does not indicate a problem in and of itself. Excessive heat can also cause fluid to darken in color. A more reliable indicator of fluid condition is the time and mileage since it has been replaced. Automatic transmission fluid will normally last at least 30,000 miles unless there are other problems.  A proper service every two-years or 30,000 mile is more than adequate.

Even very dark fluid, with no other systems or indicators does not mean there is a problem. Fluid that has not been replaced for 100,000 miles may be very dark. The automatic transmission may also still be in relatively good condition. A restricted automatic transmission filter is much more of a problem than dark fluid. This is another reason why automatic transmission flushes are ineffective.  It may also take more than one service to bring the fluid back to normal color, once it has gotten this dark.

Burnt automatic transmission will always be a symptom of a much bigger problem. The fluid will be almost black in color and have a strong burned smell. If the fluid is burnt, simply changing it will do no good. Burnt fluid indicates another problem, such as slipping clutches. A proper diagnosis and repair can prevent further damage.

Fluid color should always be considered along with other factors.  A trusted professional can let you know if there is a problem. 

 Slipping, improper shifting, noises and/or a warning light indicate a problem 

 Time and mileage are a better indicator of a need for service

 Simply flushing dark fluid is NOT a proper service

 All transmissions benefit from a proper service