Transmission Fluid Change
What is a transmission fluid change or flush?
The transmission fluid change is the tried-and-true process that your owner’s manual specifies when it calls for a transmission service. Your mechanic drains the transmission fluid, replaces the filter, then refills the transmission with fresh, new fluid. The transmission fluid change lets your mechanic get a close look at the transmission pan and the filter. This can reveal the presence of metal particles or other debris, which can indicate a bigger problem that needs to be fixed before it gets worse. This makes the fluid change an ideal preventive maintenance procedure.
The transmission flush process uses a machine to replace an automatic transmission’s fluid. Many auto repair shops own these expensive machines. The old fluid, dirt and sludge is pushed out under pressure, and new fluid replaces it. Flushing usually costs significantly more than a fluid change, due to the cost of the machine. Many shops tend to price the procedure for high profits.
Which should I get, a transmission fluid change or a flush?
The flushing process does not require the pan to be removed or the filter to be changed, so the diagnostic and preventive benefits of seeing what’s in the pan and changing the filter are lost. Additionally, many vehicle manufacturers do not recommend or require include a transmission flush as part of their vehicles’ recommended maintenance schedule. So why do it? Stick with the transmission fluid change that is specified in your owner’s manual.
However, if your maintenance schedule specifically calls for a flush, or your transmission fluid has been ignored for too long and picked up metal particles or other contaminants, a flush is the way to go.
What are the symptoms related to transmission fluid issues?
If your transmission fluid or filter gets clogged, you may notice the engine revving when you're not accelerating the vehicle — this is called transmission slipping. If you notice this, take your car in for maintenance immediately, as the damage will only get worse.
Changing the transmission fluid (and filter, if equipped) typically is a maintenance item, and should be done on a regular schedule. On some vehicles, flushing the transmission is part of the maintenance schedule; otherwise, a flush is only needed if debris is detected in the fluid.