Anyone who is even remotely involved with cars has heard this type of story – someone that they know got a transmission flush and their transmission failed within weeks or even days.
The urban legend behind this is that the “sludge” is all that was holding the transmission together and once it was removed with a flush, the transmission had no chance of surviving.
The story goes like this:
Jim was having a transmission problem, let’s say that it was sluggish in the morning and would slip on take-off from a stop from time to time when it was hot out.
Now Jim has a brother-in-law named Bob that used to work on cars, do his own tune ups and oil changes, etc. When Jim mentioned the problem that he was having to Bob, his immediate response was, “You need to get that tranny flushed.”
Of course Jim not really knowing anything about a car, much less an automatic transmission blindly follows the advice of his brother-in-law. After all Bob surely knows all about cars even though he hasn’t worked on one for over twenty years.
Jim obediently takes his car to the local lube place for a flush and an engine oil change while it’s there. Jim gets his transmission flush, pays and goes on his way.
At first, he notices maybe a slight improvement in performance but his transmission is still exhibiting most of the original symptoms.
About two weeks later Jim is driving to work and he stops to pay a toll. When he tries to pull away from the toll booth the unthinkable happens- the car just revs and goes nowhere, as if it is in neutral. Jim moves the shifter into low and is able to limp his car off to the side of the road and wait for a tow truck to take him to a transmission shop.
Here’s a list of reasons why the transmission flush myth exists:
- The myth is propagated by people who claim to be experts. I have even heard of transmission repair shops who contribute to the myth in the hopes of scaring potential customers into having their transmission overhauled rather than maintaining it.
- There are thousands of “internet experts” who promote the misinformation- it’s truly a case of “monkey see, monkey do” on steroids!
- There may have been a time in the early days of automatic transmissions when failure after a flush was more common, perhaps because of antiquated friction material and transmission fluid technology during the 1950’s and 60’s but this was before my time so I’m not able to truly discuss the legitimacy of the possibility. I can, however, say with certainty that it’s not an issue with 99.9% of the vehicles in service today. If your owner’s manual is in the glove box and not painted on the wall of a cave, you are probably good to go.
- “Sludge” is all that was holding the transmission together and when it gets cleaned out the trans in going to fail immediately. Guess what? If you have sludge in your transmission, it’s already bad and in need of a repair.
- Once in a while a flush is performed, usually at a quick lube operation, and the transmission is not refilled correctly- resulting in failure soon thereafter. Of course the incorrect fluid level is not recognized as the culprit- the transmission flush is! Many automatic transmissions have fairly complicated fluid level checking and filling procedures that are best left to a transmission repair expert to perform.
- People have unrealistic expectations. A transmission flush is no more likely to fix a failing transmission than an engine oil change is to fix a major internal engine problem. Both of these things are great to do regularly but they are maintenance- not a fix for a problem.
- The reality is that most people don’t think about their transmissions until the day that they have a problem. Jim’s transmission was on borrowed time- it was going to fail anyway but now that it has, he is going to perpetuate the myth. If he ever hears someone mention a transmission flush, he’s going to proclaim, “I had that done and my transmission blew up within a month!”
I have been in the transmission repair industry since 1987 and can honestly say that I can’t recall a single time where I saw a healthy transmission get a flush or a fluid change and subsequently have a problem. A transmission flush is the best maintenance that one can do to extend the life of your automatic transmission, don’t miss out on the benefits because of the nonsense that exists surrounding changing your transmission fluid!