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Thread: Auto tranny info.

  1. #1
    DonTom
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    Auto tranny info.

    I ran into some interesting info about automatics and how long the tranny fluid should last. I thought I should post it here:

    TRANSMISSION FLUIDS
    Automatic transmission fluid can provide up to
    100,000 miles of service before oxidation occurs
    under normal operating temperatures of about 175
    to 180 degrees F. Above normal operating
    temperatures, the oxidation rate doubles (useful life
    of the fluid is cut in half) with each 20 degree
    increase in temperature. Refer to the adjacent chart
    for petroleum base ATF.

    Note: The adjacent chart assumes that oil
    temperature remains constant for the miles
    indicated. Temperatures that appear for short
    periods, such as climbing hills, etc., would need to
    be averaged against normal operating temperatures
    to determine actual life expectancy.

    OIL TEMPERATURE MEASURE AT CONVERTER OUTLET TO COOLER:

    350 degrees F is the maximum temperature. This is the normal place to install a temperature gauge or signal. The temperature in this location will vary significantly with each vehicle startup or hill. If the temperature reaches 350 degrees F, reduce throttle. To lower the transmission
    temperature with the transmission in NEUTRAL, run the engine at 1,200 RPM for 2-3 minutes to cool the oil. DO NOT allow the converter outlet temperature to exceed 350 degrees F.

    OIL TEMPERATURE MEASURED IN THE SUMP OR OIL PAN:

    150 degrees F Minimum operating temperature for continuous operation.

    180200 degrees F Proper oil level checking temperature.

    200 degrees F Maximum oil level checking temperature.

    285 degrees F Maximum sump/oil pan temperature for short duration, such as a long hill climb.

    300 degrees F Metal parts inside transmission begin to warp and distort in varying degrees, seals melt rapidly and transmission fluid life is extremely short due to oxidation and distress.


    TRANSMISSION FLUID LIFE EXPECTANCY vs. TEMPERATURE DEGREES F MILES:

    F. miles:
    175 100,000
    195 50,000
    212 25,000
    235 12,000
    255 6,000
    275 3,000
    295 1,500
    315 750
    335 325
    355 160
    375 80
    390 40
    415 Less then 30 Min.

    -Don-

  2. #2
    Vulture of The Western World Eric's Avatar
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    Good stuff Don - thanks!

    This shows the importance of two things we rarely see in new cars:

    * A transmission temperature gauge, so you have some way of knowing whether the unit is running hot and might actually be able to do something to avoid a catastrophic failure or at least reduce wear and increase the tranny's useful life.

    * Fluid/filter changes in accordance with the above - and your specific vehicle's operating experiences, as opposed to "the book."

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