Bad Habits that Damage your Automatic Transmission

The Automatic transmission is a critical part of your car and an expensive one. As such it deserves optimum care, but sadly many car owners (even some mechanics) consistently engage in practices that will break even the toughest tranny! Described below are 8 bad habits that will ensure your transmission functions less efficiently and most likely fails…ultimately.

These are habits will be listed under 2 basic categories:

A. Fluid Management 

B. Driving Habit

A. Fluid Management: Automatic Transmission Fluid (ATF) is to the transmission what blood is to humans! ATF serves to lubricate and cool the transmission. Proper fluid management (all other things being equal) will ensure your transmission functions optimally and lasts longer. Under this category we will consider 6 out of the 8  evil #coughs# bad habits.

1. Incorrect ATF type for transmission: There are several kinds of ATFs specially designed to meet the needs of the different automatic transmissions from auto manufacturers e.g. Dexron*, Mecron*, ATF Type IV, ATF DW-1 etc. The list is endless! Some manufacturers recommend only OEM fluids. Whatever be the case the ATF specification will be found in the owner manual.  Incorrect fluids will not lubricate and cool the a transmission as required and heat breaks transmissions. Oils above a certain temperature will degrade and loose some of their property as lubricants. Just imagine someone dumping some generic ATF fluid into a 4Matic Mercedes Benz car. Honda transmissions are specially unforgiving for using the wrong fluid type!

(*have different sub-types)

ATF refill

ATF refill in progress on my 2003 Honda Accord

2. Under-filling with ATF: Each transmission has the correct volume of ATF that it’s supposed to hold. Under-filling a transmission simply means there’s not enough lubricant, meaning that heat will prevail in destroying sensitive components of the transmission.

3. Over-filling with ATF: This will increase the pressure of the fluid within the transmission case and predispose your transmission to leaks. It may also cause slipping thus affecting shift quality. I once met a neighbor about to add ATF to his car early in the morning. Funny thing was that the ATF was already more than 5cm past the max mark! According to him, adding more fluid will prevent him from doing a second transmission replacement. No wonder he lost the first!

4. No/irregular ATF changes: Most oils will loose their capacity as lubricants over time, ATF is no exception. The heating cycles of ATF will wear the fluid with time. Not keeping the recommended ATF change intervals translates to poorer lubrication and insufficient cooling.

5. Use of Additives: These are additional compounds that range from friction modifiers to stop-leak products etc. developed by third parties and marketed to for some specific purpose. I do not attempt to discredit any product, but my simple advice to car owners on use of additives is; what does your car manual say about use of such? If not recommended stay clear.

6. Transmission Flushes: Some people love this. But If you must, find out the recommended way of doing so according to your manufacturer.  Honda (at least for the 2003-2007 Accord) recommends against flushing using external pressure. Some have developed problems after such flushes. Honda rather recommends doing the X3 drain and fill to serve as a flush.

B. Driving Habit: How you drive can also determine the service life of your automatic transmission. Pushing machines to the upper limit of their capacity, consistently really isn’t the best. These driving habits take the ATF temperature beyond design limits.

7. Leaving your transmission in Drive in traffic: Many often do this, the gear is left in Drive with the brakes slammed down to prevent movement. This simply builds up heat which eats away at your tranny.

8. Changing between Reverse and Drive while in motion: While it may feel cool and make you seem like a star out Fast & Furious, your transmission was designed to switch from R to D or vice versa from a stand still. Not heeding this, means you use your transmission as the brakes and it simply wasn’t designed for such “Vin Diesel” moves.

Hope you found these few tips helpful. All the best!



  • jinse


    Just in case yours is missing you can visit to see if you can find a free copy.

  • segun

    Thanks for this great piece. Please, where can I get the recommended ATF for a modern Honda Accord car? Thanks

    • Thanks Segun.
      Honda upgraded to ATF DW-1 for all its automatic transmissions. It’s not to be used for CVTs, that has its own fluid.
      ATF DW-1 is now available locally in some select shops. You can also find it online on if you don’t get it in a store.
      Beware of sellers who still stock ATF AZ-1 and would quote the owners manual. The AZ-1’s in the market are fake as Honda no longer makes it.

  • Seyi J.

    Very good and enlightening job. If I may ask, what is the best / recommended ATF for a ’96 4Runner [4 X 2]?

  • stec

    Vin Diesel moves indeed. Good one Piyke. Thanks for the tips…especially the one about slamming down on the brakes with the car still in ‘drive’ while in traffic. I do it all the time. I actually thought putting it to neutral and then moving it back to drive as the traffic eased up would kill my transmission faster. Thanks Piyke

    • Piyke

      Thanks Stec. I’m sure you’ll glad to know that you’ll save fuel as well by moving to Neutral when in traffic!
      All the best

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