Toyota-Automatic Transmission Flush
Toyota Automatic Transmission Fluid Toyota proper is largely silent on when to change the fluid in automatic transmissions under normal driving conditions.
They only say to inspect and advise. We recommend changing your automatic transmission fluid by means of flushing it as preventative maintenance every 30,000 miles, or sooner if the fluid has gone through a significant color change that indicates its condition has begun to deteriorate.
The old fluid can’t be effectively removed by simply draining. Due to the torque converter not draining, most of the fluid remains in the system even if the pan is removed.
The most effective way to accomplish a complete changeover of the transmission fluid is to flush the entire system. This is important for the life and health of your vehicle, and far more economic than having to spend the thousands required replacing or rebuilding your transmission later.
The question is occasionally raised as to whether changing or flushing the transmission can create any problems, particularly in the case of a vehicle that is long overdue for a fluid change. In more than 16 years of performing this service I have never been aware of any negative consequence that could remotely be perceived as a consequence of changing the transmission fluid. I don’t recall even any transmission incident that might have been perceived as an unfortunate coincidence after changing the fluid. The way we flush the transmission is really nothing more than a very thorough fluid change.
After draining the pan, we use the transmission’s own pump to pull in new fluid and push it through the system in its normal direction of flow, pushing out the old fluid ahead of the new. New fluid is pumped through the torque converter and on out through the cooler to where we catch it in a drain pan. What could be a more natural or harmless way to change your transmission fluid?
Some shops use machines in the flushing process that may introduce other variables into the process than what I’ve described as our process. Some of these variables might include special solvents and higher than normal pressures. Although I hear people talk about back-flushing, I’m not aware of whether any of the standard processes actually involve reversing the fluid flow. I can’t say from personal experience whether these alternate processes increase the risk of creating an unintended problem or not.
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