Taking care of your car or truck’s transmission is important for its long-term health. But all too often, car owners misunderstand the basic maintenance that’s needed to keep a gearbox running smoothly.

Do You Need to Have the Transmission Fluid Changed?

The simple answer is yes. But service intervals for new vehicles can exceed 100,000 miles before this needs to be done. Getting the fluid replaced is certainly going to cost you less than replacing a transmission that has been left in the lurch by skimping on service requirements. Failing to properly maintain your car’s transmission could leave you stranded and with a big repair bill.

Other than regular service, your transmission might be due for some important repairs—or have an extended warranty—because of a past recall.

How Often Do You Need to Have the Transmission Fluid Changed?

The best advice is to know your car and the manufacturer’s recommended service intervals. It’s worth noting that intervals for changing transmission fluid vary widely. For some cars and trucks, it can range from as little as 30,000 miles to more than 100,000 miles. Some new vehicles, especially those fitted with automatic gearboxes, have transmissions that are almost sealed shut, with fluid that’s meant to last the lifetime of the car. It is worth noting that even on these units though, a drain plug is provided for servicing.

Most CVTs (continuously variable transmissions) need inspections and/or fluid changes. We advise owners to refer to the owner’s manual for specific guidance and to keep records of related services. You can always give us a call at O’Neill auto & Transmission Service, we would be happy to advise you.

Remember that unlike engine oil, transmission fluid should never burn off. And a tell-tale sign of a transmission leak is a puddle of red liquid on the ground, usually under the middle or front of the car.

Should Your Mechanic Flush the Transmission Fluid?

First, it’s helpful to understand the role transmission fluid plays in a car’s operation. Transmission fluid helps keep mechanical components cool and lubricated, whether the gearbox is automatic or manual. Over time, the transmission’s interior components wear down, and tiny particles contaminate the fluid. This could potentially lead to damage.

Getting rid of this dirty fluid makes sense, right? If it’s called for in the service manual, go ahead and let your mechanic do the job. There is also a distinction between simply draining and refilling a transmission vs. power-flushing the system.

Does a Manual Transmission Need Fluid, Too?

Yes, even a manual needs transmission fluid. The type of fluid can vary from car to car, however. Some manuals require conventional engine oil, and others function best with automatic transmission fluid. So make sure you’re putting in the fluid that’s specified for your car.

How Do You Know Whether the Transmission Fluid Needs to Be Changed?

Checking transmission fluid isn’t always easy. In many cases, it’s necessary to have a mechanic put your car on a lift for examination. Some cars have a transmission dipstick or reservoir in the engine bay, so check under the hood first. Even though fluid levels might look fine, it could be more difficult to discern whether there are pollutants or small metal particles in the fluid.

Separating transmission maintenance from breakdowns is trickier. In a malfunctioning automatic, gearshifts might become more abrupt and occur at awkward intervals. For a car with a manual gearbox, the feel and action of the gear lever could become stiffer and balkier in regular daily operation. These types of problems probably indicate an issue with the gearbox itself. If you experience any of them, let your mechanic know right away.

Is Changing the Transmission Fluid an Easy DIY Job?

It can be a complicated and messy task for the average car owner. Accessing the transmission can require ramps, jack stands, or a lift. Many modern cars have transmissions that are basically sealed tight or require a dealer’s service computer to read temperature or other parameters, making them all but impossible to work on for the average do-it-yourselfer. Trust our transmission professionals, we’ve been handling transmission issues since 1960!

In part by Consumer Reports