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Transmission Flush

A transmission flush is a debatable procedure, as it comes with its pros and cons. Read on and decide whether to go for it or not.
Suketu Mehta
Few people recommend this procedure, as they believe it improves the working of the car engine, while others feel that the process damages the car engine. Transmission fluid is a specialized oil used in automatic or manual transmissions. It meets all requirements of the transmission system and is necessary for valve operation and gear lubrication.
Over a period of time, the oil has the tendency to get dirty, and as a result, its effectiveness gets hampered. It is recommended to change the oil after every 30,000 miles. However, due to the prevalent confusion on the same, read the information given here and then decide whether to opt for a transmission flush or not.


It is a procedure through which most of the old transmission fluid is cleared out from the vehicle. Converters, cooler lines, and coolers, which are part of the transmission system, are drained out of any residue of the old fluid. Although flushing procedure is debatable, it is believed that the process does enhance the functioning of the motor.


There is a confusion among people about fluid change and the flush. In fluid change, a drain plug is unplugged, and this allows the old fluid to flow out, which is collected in a container.
This process is definitely useful in draining out majority of the old fluid, but does little when it comes to cleaning the system. This results in some amount of old fluid already being present inside the system, which mixes up with the new fluid when entered, thereby reducing effectiveness of the latter.
In a transmission flush, a machine is attached to the cooler lines, which injects a strong cleansing agent through the system, which cleans up any accumulated junk.
A fluid change is a safe process. It involves using the transmission pump to enter new fluid into the system, which starts to force the old fluid out of the system. Thus, a simple displacement procedure is used in fluid change rather than applying pressure in the system to get rid of old fluid.
On the other hand, the flushing procedure is not considered safe for the engine due to the various problems, which are discussed here.


The process is done with help of machines, and involves introducing high pressure cleaning solvents through the engine and the system, which cleans up any collected junk from the system. However, car engines have tiny passages through which the fluids or oil pass.
When a strong cleaning agent is used for the flush, it degenerates the junk collected in the system, which passes though these delicate passages, at times, blocking or damaging them. This results in an abnormal fluid flow, which reduces lubrication and varied shifting pattern in the system.
The car owner then has to undertake other major car repair jobs like engine replacement, to solve the issue.

Average Cost

The average price of this procedure ranges from $100 - $250 depending on the car model. For low cost cars, the cost will be less compared to more expensive cars. It also depends on where the job is being done. Ensure the place has standard equipment. Use only the original fluid while replacement, as any other fluid could damage the system.

Is it Really Necessary?

There are numerous car dealers who say it is absolutely necessary to do this procedure. But, this is not at all true. Various top car manufacturing companies do not recommend it as a part of the regular maintenance procedure.
Car dealers want to sell the fluid or flush machines, and hence, coax car owners to go for it. In fact, in the flush machine manuals, it is implicitly stated 'do not use the machine on high mileage vehicles'.
Rather than opting for a transmission flush, it is better to change the engine oil and oil filters regularly. Doing this will prevent any problems from arising, and there will be no need for doing the complete flush. In case it is absolutely necessary, do it from a reputed mechanic and pray hard the engine and system do not give in.