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  1. Join Date
    Oct 2002
    How to keep the automatic transmission alive

    How often to change transmission fluid • How to use the overdrive • How not to damage the transmission
    Note, the information contained in this guide is for educational purposes only and cannot substitute for the advice of professional mechanic or authorized dealer. Different cars have different requirements; for information specific to your car consult your owner's manual or call your local dealer.

    The automatic transmission is one of the most complicated and thus one of the less reliable parts of the vehicle. The repair of an automatic transmission is complex and tends to be quite expensive. More than that, automatic transmission problem can make your car unsafe - some transmission defects may cause, for example, that the car can roll with the shifter in Park or drive forward with shifter in Neutral.

    On the other hand, if taking a good care of, your transmission can last you really long with no significant problems.

    In this article you may find some simple tips how to prevent your automatic transmission from damage and keep it in a good shape. It doesn't require too much of your efforts - just periodical checking and regular maintenance.

    Tip: Have you looked in your vehicle owner's manual? Try, it's a best source of information on your vehicle maintenance. You will be amazed how many useful info you may find in this book! Having more questions? Don't know what type of fluid to use? - just call local dealer service department and ask them, they have all the information and they will be pleased to help you.

    • What can damage your transmission
    • How to prevent automatic transmission from damage
    • How to use overdrive
    • Servicing your transmission
    • When it's time to visit the transmission shop
    • Where to find repair information, diagrams, specification, etc.

    What can damage your automatic transmission

    Most of the transmission troubles start from overheating. Under heavy load, such as towing a heavy trailer, rocking the vehicle from the snow, having continuous stop and go traffic in hot weather, racing, etc. the transmission overheats. At higher temperatures the transmission fluid burns loosing its lubricating qualities and becomes oxidized leaving deposits all over inside the transmission.

    Exposed to the heat the rubber seals and gaskets inside the transmission become hardened causing leaks. The metal parts warp and loose their strength. All this, sooner or later, results in transmission failure. For example, a friend of mine burnt the transmission when he was spinning the wheels too hard trying to free his shiny Audi from the snow on the next day after he bought it!

    However, overheating is not the only reason - sometimes transmission breaks down because of poor design, due to lack of maintenance or after being rebuilt by inexperienced technician. Few other reasons: harsh driving, too low or too high transmission fluid level or wrong transmission fluid type - a person I know added gear oil into the automatic transmission... guess, what happen? - the transmission died after 40 minutes of driving!

    How to prevent the transmission from damage

    - Regularly check your parking space for leaks. Doesn't matter, is it the engine oil leak, power steering fluid or transmission fluid; if you discover any, get it fixed before it caused something serious.

    - Once in a while check the transmission fluid level and condition. Not all cars however have the automatic transmission dipstick, in some cars, for example, in late Volkswagen models, the transmission fluid can only be checked by the dealer. Consult with your owner's manual for details. If the transmission fluid level is too low, there is a leak somewhere that needs to be fixed.

    - Change the fluid as often as it said in your owner's manual or when it becomes too dark (rather brown than red) or dirty.
    Also, keep in mind that an automatic transmission can not be drained completely - there is always some transmission fluid left inside the transmission (the torque converter, in the valve body, etc.) which means you only can change about 60% of the fluid at once. This is one more reason to change it more often.

    - Use only the same type of the transmission fluid as specified in the owner's manual or on the dipstick. Some vehicles (eg. Dodge Caravan) are very sensitive to fluid type

    - Never shift to the Reverse or Parking until the car comes to a complete stop.

    - Never shift from the Parking mode when engine rpm is higher than normal idle.

    - Always hold a brakes down when shifting from Parking.

    - The automatic transmission can be damaged if towing with the drive wheels on the road. Always use a dolly or place powered wheels on the towing platform (if the vehicle is front wheel drive - tow it from the front leaving rear wheels on the road.

    How to use overdrive

    Generally speaking, overdrive (O/D) is the highest gear in the transmission. On most cars the automatic transmission has 3 speeds and Overdrive (forth speed). Overdrive allows the engine to have less rpm with higher speed in order to have better fuel efficiency. When you switch it on, you allow the transmission to shift into overdrive mode after the certain speed is reached (usually 30 - 40 mph depending on the load). When it's off, you limit transmission shifting by third speed.

    In normal driving condition the overdrive should be always on. You may need to switch it off if you drive in mountains area.

    [The automatic transmission automatically shifts from OD to the 3-th gear when it feel more load. When it feels less load it shifts back to the O/D, but under certain conditions, e.g: driving uphill or towing a trailer, the transmission can not decide to stay in OD or to shift into 3-th speed and it starts to shift back and forth. That's the time you may switch it off and help the transmission to decide.]

    You also may need to switch it off when you want to slowdown using the engine braking, for example, driving downhill. [For more details, check your owner's manual]

    Servicing your transmission

    I'd recommend to go for a service to your car make dealer - they have original parts, they know exactly what type of the fluid to use and their technicians are highly trained to service particular vehicle model. Even if you go to the independent garage, always ask to use original parts - sometimes, the aftermarket parts are not of as good quality as original.
    When it's time to go to the transmission shop

    If you experience any problems with your transmission such as leaks, noises, problems with shifting, etc. - don't wait until the problem will become worse and car will finally stop somewhere on a highway, visit your trusted local transmission shop.

    Automatic transmission problems never disappear by themselves. Also, when going for the repair, try to explain to service person more detailed - what exactly problem you experience, when it happens, what does it look like. It will be easier for them to repair the transmission. Before going to the transmission shop for the repair ask them about the warranty - the longer warranty they will give you, the better will be the repair.

  2. Join Date
    Oct 2002
    How to check the transmission and discover possible transmission problem when buying a used car.

    • How to check an automatic transmission when buying a used car
    • How to check manual transmission
    • How to check automatic transmission fluid
    • Checking CV joints

    Please note, the information below is designed to give you an initial idea about what to look for when buying a used car and may help you to eliminate some used cars with potential problems, but it can not substitute detailed mechanical inspection performed by a professional. As a final step before purchase, take the car to a mechanic of your choice for thorough mechanical inspection.

    An automatic transmission becomes more reliable these days, but still it's most-easy-to-break and most-expensive-to-fix part of the vehicle. If heavily abused, the automatic transmission can be easily destroyed within half an hour. For example, a friend of mine burnt the automatic transmission in 20 minutes when he was trying to free his shiny Audi from the snow in the next day after he bought it! it cost him about $2000 to rebuild it and after one year it broke down again.

    Also, an automatic transmission is very sensitive to the fluid quality and condition. Improper fluid type can damage the transmission. A person I know added a gear oil into the automatic transmission, guess what - 30 minutes of driving was enough to destroy the transmission. Obviously, when buying a used car, the automatic transmission is one of the most important parts to check. Make sure to have the car inspected by a mechanic before you made final decision, it will well worth it.

    At the beginning

    First, check the used car history records; it may save you some time and money. If the history report shows that the car you want to buy was used as a rental vehicle or has been involved in an accident, there is no point to even look at it.

    How to check a used car history report

    Ask the previous owner or salesperson if any repair has been done to the transmission.

    If the automatic transmission is already rebuilt, try to avoid buying such a car. It's not like all rebuilt transmission will have problems - some of them work even better than before. The problem is that not all transmission shops can do equally the same high-quality job. And since there is no way to verify if it was rebuilt properly or not, it's better not to take chances. Another thing to be concern about, ask if the car you are looking for was used for towing a trailer. I've seen many cars that were used for towing a trailer with excessively worn transmission.

    How to check an automatic transmission

    Automatic transmission fluid

    First, check the transmission fluid level and condition. If you don't know how to do it, here is an illustration:

    How to check the automatic fluid

    With the engine idling, transmission in "Parking" (some car may have different procedure, refer to owner's manual) remove the automatic transmission dipstick and wipe it out with the tissue. Then insert it back and pull out again. Look at the fluid very closely. It helps to drip the fluid on a white paper to be able to see fluid condition. The fluid on the paper should be clean and transparent, without any metal filings or black flakes. New fluid comes red. Over the time and use it become more brownish, but it shouldn't be black. Look at the image on the left.

    Try to smell the fluid. It should not have a burnt smell.

    All this may seem to be difficult for you but when you check few similar cars, you'll be able to see the difference.

    If you discover that transmission fluid is too dirty or black, or smells burnt, avoid buying such a car.

    However, some modern cars simply don't have the transmission dipstick. In this case, the only way to check it is a test drive.

    Automatic transmission test drive

    Use more caution when test-driving someone else's vehicle - the mirrors, the driver's seat, etc. may not be adjusted properly for you. First, get use to brake pedal feeling, adjust the mirrors, driver's seat, and learn all the controls of the vehicle. Proceed to drive only when you sure it's safe.

    One of the indications of a transmission problem is delayed engagement, when there is a long delay between you shift the shifter into "D" or "R" and the transmission kicks in.

    It's easier to note delayed engagement after a car was sitting for a while: With the transmission in "P" (Park) start the engine, and wait until the engine rpm has reduced to normal level (650 - 850 rpm).

    With your foot holding down the brake pedal, shift to the "D" (Drive) position. Almost immediately the transmission should engage - it feels like the car wants to creep forward. This should happen very smoothly, without a strong jerk or clunk.

    Shift to "N" (Neutral), and the transmission should disengage. Now, shift to the "R" (Reverse) position. Again, the transmission should engage without a delay - you will feel the car wants to creep backward. This also should be very smooth, without a strong jerk.

    If there is a notable delay (more than 1 seconds) between the moment you shift and the moment the transmission engages, such a transmission is either too worn or has some problem, avoid this car.

    If there is a strong jerk or noise while shifting, avoid buying such a car. Now, still holding the brake pedal down, try to shift from D to R and back. There should be no strong jerk.

    Shift to the "D" position, and try to drive gently, with smooth and gradual acceleration. Until the vehicle reaches a speed of 50-60 km/h or 30-37 mph, you should feel the gears shift at least twice (from first to second, and from second to third). These shifts should be made very smoothly, without jerks or slipping.

    By "smooth shift" I mean it should be smooth but you should feel it at the moment the rpm drops down; it feels like the car slows down for a very short instance and then accelerates again. You also can note the transmission shifting moment by the slight change in the engine tone.

    But when the transmission is extremely worn it may shift with quite a strong jerk, shudder or a delay (especially from first to second speed).

    Driving at a speed of 40-50 km/h or 25-30 mph, if you press down the accelerator pedal for a few seconds, you should feel downshifting to the lower gear, if the automatic transmission works properly.

    The next step: check overdrive.

    While driving at 60-70 km/h or 35-45 mph on a level road, without using the accelerator, switch overdrive ON. You should feel an upshifting to the next speed. Switch it to "OFF," and you should feel a downshifting.
    Another thing that may indicate the transmission problem is the slipping. When the transmission is excessively worn it may slip - which means you press the accelerator, the engine rpm increases but the speed remains the same.

    If during the drive test you feel any problem such as transmission seems to slipping or shifts with a jerk or shudder or if the transmission got stuck in some gear, or has trouble shifting into a particular gear (for example, from second to third), avoid buying such a car.

    Test-drive the car as long as possible. Often the transmission may work well when it's cold but when it's warmed up it starts giving troubles. So, it's better to spend more time checking the transmission than later fixing it endlessly. Normally there should be no shudder, no noises or any kind of strong jerks at any speed and at any engine temperatures while any shifting. If the salesperson tells you that the jerks or shudder or any other abnormal transmission behavior is "normal" for this car or it's just because the car is cold or anything alike, never trust them. The warranty they give you doesn't mean that the transmission won't break. It only means that may be dealer will take care of the car if it will break. Plus, a rebuilt transmission in many cases doesn't last too long.

    Check the CV joints

    Broken CV joint boot

    An OK CV joint boot

    A Constant Velocity joint or CV joint is an important component of the drive train. The CV joint is packed with grease and protected by the rubber or plastic boot.

    Most common problem with the CV joints is when the protective boot gets damaged. Once this happens, the grease comes out and the moisture and dirt come in, eventually causing the CV joint to fail due to lack of lubrication and corrosion.

    In worst case, the CV joint may disjoin causing the vehicle to stop running.
    You can check the condition of the CV joint boots visually. You can see them with the front wheel turned outside, looking down from the front of a car. None of them should be damaged. Look at the photos. The CV-joint boot in upper image is damaged, in the lower image it looks OK. If a boot is damaged, it has to be replaced as soon as possible. If continue driving with broken boot, the CV joint or a whole drive shaft will need to be replaced.
    While drive test, If you hear clicking or popping noise when turning, the CV joint is probably already defective.

    Have the car inspected by a mechanic

    Before making your final decision, have the car inspected by a mechanic. There are many things that only an experienced mechanic will be able to reveal.

  3. Join Date
    Oct 2002

    Automatic Transmission Fluid
    By Larry Carley C2006

    Watch out for "pink stink," the burned odor that indicates trouble inside an automatic transmission.

    The next time you check the fluid level in an automatic, sniff the fluid on the end of the dip stick. If it smells like burned toast and/or has a discolored brown appearance, the fluid has cooked itself and is no longer capable of providing proper lubrication to the transmission. If you're lucky, you may have caught the problem before serious damage has been done -- but more often than not by the time the fried fluid is discovered, the transmission is also toast.

    Compared to motor oil, ATF has live pretty easy. There's no soot, gasoline or condensation from combustion blowby to contaminate the fluid. The only physical contaminants the fluid must deal with are particles that wear off the friction plates, gears and bearings inside the transmission. Most transmissions have some type of internal filter to keep the fluid clean. Some do a pretty good job, but others don't. Most Asian transmissions only have a plastic or metal strainer that can only trap the larger pieces of debris. The rest circulates with the fluid and accelerates wear. Changing the fluid is the only way to get rid of these contaminants.

    Heat is the main concern for ATF. Automatic transmissions create a lot of friction, and friction produces heat. The fluid is constantly churning inside the torque converter and being pumped through metering orifices and hydraulic circuits. Every time the transmission shifts gears, the clutch packs generate even more heat that must be carried away by the fluid. The greater the load on the transmission, the more heat it generates and the hotter the fluid gets.

    Most ATF can withstand normal operating temperatures of around 200 degrees F for tens of thousands of miles. But if the temperature of the fluid rises above 220 degrees F the fluid starts to break down quickly. Above 300 degrees, fluid life is measured in hundreds, not thousands of miles. And above 400 degrees, the fluid can self-destruct in 20 to 30 minutes!

    ATF contains ingredients to improve its oxidation stability as well as other additives to reduce foaming and inhibit corrosion. Over time, the protective additives can also break down causing the fluid's lubrication properties and viscosity to change for the worse. That's why fluid breakdown is the leading cause of transmission operating problems and failure. Most experts still recommend changing the fluid and filter every 2 to 3 years or 24,000 to 36,000 miles -- or once a year or every 15,000 miles if a vehicle is used for towing or other severe service use.


    The first thing to check is the fluid level. For an automatic transmission to function normally, the fluid level must be between the "full" and "add" marks on the dipstick. If the fluid level is low, the transmission may slip or engage slowly. If the level is too high, the fluid can become mixed with air (aerated) causing shifting problems, slippage and noise.

    Check the level when the transmission is hot. On most vehicles this is done with the engine idling and the transmission in Park. Moving the gear selector thorough each gear position prior to checking the level will help assure an accurate reading.

    Under normal driving conditions, a transmission should not use any fluid. A low level, therefore, usually indicates a leak. A visual inspection of the pan gasket and driveshaft seals will tell you where the fluid is going.

    Next, check for fluid oxidation. The sniff test is a good one, but a "blotter test' is even better. Put a few drops of ATF on a clean paper towel. Wait 30 seconds, then examine the spot. If the fluid has spread out and is pink, red or even light brown in color, the fluid is in satisfactory condition. But if the spot hasn't spread out and is dark brown in color, the ATF is oxidized and should be changed.

    If the fluid has a milky brown appearance, it indicates coolant contamination. There is probably a leak in the ATF oil cooler inside the radiator that is allowing coolant to mix with the ATF. This is bad news and needs to be repaired immediately.

    If the fluid is full of bubbles or is foamy, the transmission is probably overfilled with ATF. Other causes include using the wrong type of ATF or a plugged transmission vent.


    The "old fashioned" way to change ATF is to drop the pan, drain the transmission, replace the filter, reinstall the pan and refill with fresh ATF. Though better than nothing, this approach can leave up to two-thirds of the ATF trapped inside the torque converter (unless the converter has a drain plug, which few do).

    A better approach is to use equipment that either attaches to the ATF oil cooler lines or the filler tube to exchange new fluid for old. This approach will replace all of the old fluid. The filter should also be changed to get rid of trapped contaminants, too, because a plugged filter can cause the same kind of problems as a low fluid level or low line pressure.

    Always use the type of ATF specified by the vehicle manufacturer. If you don't know, refer to the owners manual or a reference chart. The type of ATF may also be specified on the transmission dipstick.

  4. Join Date
    Oct 2002

    Over the years, there have been a confusing array of different ATF types and specifications. Make sure the replacement fluid meets or exceeds all OEM requirements. Using the wrong type of fluid may cause transmission problems and damage.

    Type F -- Introduced by Ford in 1967 for their automatics. Also used by Toyota.

    Type CJ -- Special Ford fluid for C6 transmissions. Similar to Dexron II. Must not be used in automatics that require Type F.

    Type H -- Another limited Ford spec that differs from both Dexron and Type F. Can be replaced with Mercon.

    Mercon -- Ford fluid introduced in 1987, very similar to Dexron II. Okay for all earlier Fords except those that require Type F.

    Mercon V -- Ford's newest type, introduced in 1997 for Ranger, Explorer V6 and Aerostar, and 1998 & up Windstar, Taurus/Sable and Continental. Must not be used in 1997 or earlier Fords.

    Dexron -- General Motors original ATF for automatics.

    Dexron II -- Improved GM formula with better viscosity control and additional oxidation inhibitors. Can be used in place of Dexron.

    Dexron IIE -- GM fluid for electronic transmissions.

    Dexron III -- Replaces Dexron IIE and adds improved oxidation and corrosion control in GM electronic automatics.

    Dexron III (H) – Improved version of Dexron III released in 2003.

    Dexron III/Saturn -- A special fluid spec for Saturns.

    Dexron-VI – For 2006 GM Hydra-Matic 6L80 6-speed rear-wheel-drive transmissions, can also be used in 2005 transmissions that require Dexron III but is NOT recommended for older transmissions or Saturn VUE transmissions.

    Chrysler 7176 -- For Chrysler FWD transaxles.

    Chrysler 7176D (ATF+2) -- Adds improved cold temperature flow and oxidation resistance. Introduced 1997.

    Chrysler 7176E (ATF+3) -- Adds improved shear stability and uses a higher quality base oil. Required for four-speed automatics (do NOT use Dexron or Mercon as a substitute).

    Chrysler ATF+4 (ATE)– Introduced in 1998, ATF+4 is synthetic and replaces the previous ATF+3 fluid. Used primarily for 2000 and 2001 vehicles, it can also be used in earlier Chrysler transmissions (except 1999 and older minivans with 41TE/AE transmission). ATF+3 should continue to be used for 1999 and earlier minivans because of the potential for torque converter shudder during break in.

    NOTE:Chrysler ATF+4 Must always be used in vehicles that were originally filled with ATF+4. The red dye used in ATF+4 is not permanent. As the fluid ages it may become darker or appear brown in color. ATF+4 also has a unique odor that may change with age. Therefore, do not relay on the color and odor of ATF+4 to determine if the fluid needs to be changed. Follow the OEM recommended service interval.

    Chrysler ATF+5 for 2002 and newer models.


    BMW LT7114l or LA2634 -- Special forumla for BMW transmissions.

    Genuine Honda ZL ATF -- Special ATF for Honda automatics (except CVT applications).

    Mitsubishi Diamond SP-II & SP-Ill -- Special formula ATFs for Mitsubishi transmissions.

    Nissan J-Matic --– Special forumla for Nissan transmissions.

    Toyota Type T, T-III & T-IV -- Special formula ATFs for Toyota and Lexus transmissions.

    NOTE: There are a number of aftermarket synthetic ATF fluids that claim to meet numerous OEM requirements. Refer to the product label for approved applications.

  5. Join Date
    Oct 2002
    Automatics with No Dipsticks

    According to the automobile manufacturer’s research, a certain percentage of automatic transmission failures are caused by over-filling and/or using the incorrect transmission fluid. It is important to remember to NEVER over-fill the transmission assembly and to ALWAYS use the recommended transmission fluid. To discourage over-filling, some vehicle manufacturers have eliminated the dipstick on the transmission. Unfortunately, this also makes it hard to tell if the fluid level is low.

    On automatic transmissions that do not have a dipstick to check the fluid level or add fluid, a fill plug is usually located on the left side or right side of the transmission. On some, there may also be a drain plug on the bottom of the transmission.

    To check the fluid level, the transmission must be warm and the vehicle must be parked on a level surface or raised on a lift. Jacking up the front wheels will tilt the vehicle and give an innaccurate indication of the fluid level. Therefore, all FOUR wheels must be raised off the ground and the vehicle must be properly supported by four jack stands. NEVER crawl under a vehicle unless it is safely supported by jack stands.

    When the fill plug is removed, some fluid should dribble out of the hole if the fluid is at the proper level (flush with the bottom of the fill plug hole). If no fluid comes out, add fluid to bring it up to the level of the hole.

Automatic Transmission FAQ