Tall-Tale Signs that Your Car Needs a Transmission Flush

When was the last time that you flushes your car's transmission? Many drivers rarely, if ever, do it, resulting in grimy sludge-like oil that fails to properly lubricate the transmission. Here are some tall-tale signs that it's time to flush the old oil from your transmission and replace it with new oil.

Warning Lights

The majority of cars and trucks manufactured after 1990 are equipped with sensors to identify mechanical problems, including problems associated with the transmission. If your car needs a transmission flush, it may produce vibrations that are recognized by these sensors, alerting you in the form of a warning light on the dashboard. Use a code reader to determine what the warning lights mean and whether or not it's associated with the transmission.

30k Miles

A good rule of thumb is to flush your vehicle's transmission at least once every 30,000 miles or 2 years, whichever comes first. Over time, oil within the transmission will pick up dirt, brake dust, debris, and other impurities, turning into a sludge-like consistency. When this occurs, it will be less effective at lubricating the internal components of your transmission and wicking away heat. You can keep your vehicle running smoothly, however, by flushing the transmission once every 30,000 miles or 2 years.

Related Reading: Diagnosing Automatic Transmission Problems

Difficulty Changing Gears

Of course, another tall-tale sign that your car needs a transmission flush is difficulty changing gears. If there's too much dirt and sludge present, it will may cause a slight delay when you change gears. And in manual transmission engines, it can make changing gears even more difficult -- or in some extreme cases, impossible. Pay attention to your vehicle when changing gears to see if there's a delay, as this could be indicative of it needing a transmission flush.

Slipping Gears

Slipping gears may also indicate the need for a transmission flush. A dirty transmission will result in less hydraulic power, which in turn may cause gears to slip. The transmission must have adequate pressure to stay on the specified gear. And when it lacks this pressure, you may "slip" out of gear -- a sign that it's time to flush the transmission.

These are just a few common signs that your car needs a transmission flush. Keep in mind that your car may appear to function normally even if the transmission oil is dirty. So, try to flush the transmission at least once every 30,000 miles or 2 years. And if you notice any of the aforementioned symptoms, go ahead and flush it.

Related Reading: Transmission Flush vs. Fluid Change