Transmission questions

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  • 1 Post By Ludacrisvp
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  • 1 Post By MoistCabbage
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Cadillac STS Forum - 2005 through 2012 Discussion, Transmission questions in Past Cadillac Vehicle Discussion; Hi, I spent lot of time to brows forum and I'm still confused about few things. 1. What code of ...
  1. #1
    Wojciech is offline Cadillac Owners Fanatic
    Automobile(s): Cadillac STS 3.6 DI 2009 RHD with Performance Pkg
    Join Date
    Feb 2014
    Southampton, UK

    Transmission questions


    I spent lot of time to brows forum and I'm still confused about few things.

    1. What code of transmission I have (6L45, 6L50, 6L80, 6L90)? STS 2009 6 SPD 3.6 DI
    2. I have 72k miles on it. Should I change fluid. What is interval time in approach? I know some saying it's not essential because it is a life time fluid. But I don't really believe it.
    3. Should I flush it or drain ?
    4. What oil is the best for this transmission? Dextron IV?
    5. What filter is the best quality, what brand I mean?

    Basically car run smooth, but I would like to prevent for fast wear and extend life of this part.


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  3. #2
    Ludacrisvp's Avatar
    Ludacrisvp is offline Cadillac Owners Connoisseur
    Automobile(s): 08 STS4 V8 F55 1SG Euro tails & 01 Monte SS Pace Car
    Join Date
    Feb 2009
    St Michael, MN

    Re: Transmission questions

    1. it should be 6L50
    2. I believe its called for at 50k or 100k depending on how hard you drive it, if you are thinking about doing it then I would do it.
    3. drain and refill only.
    4. not sure
    5. not sure
    mckellyb likes this.

  4. #3
    Guy.Seminerio is offline Cadillac Owners Connoisseur
    Automobile(s): 2009 STS-V; 1979 Coupe Deville, 2012 Chevy Cruze Eco Manual
    Join Date
    Feb 2013
    Whitestone, NY

    Re: Transmission questions

    According to the manual the changing of the Trans fluid and filter is done every 100k miles unless use of the car is categorized as "severe" in which case it's every 50k miles. It then goes on to define severe as:

    Change automatic transmission fluid and filter if the vehicle is mainly driven under one or
    more of these conditions:
    − In heavy city traffic where the outside temperature regularly reaches 90°F (32°C) or higher.
    − In hilly or mountainous terrain.
    − When doing frequent trailer towing.
    − Uses such as limousine service.
    − Uses such as high performance operation.

    If I were you I'd go ahead and have it done if you're not the first owner of the car.

    Not sure about your other questions either. I've only had the dealer do it.


    And no flush.
    mckellyb likes this.

  5. #4
    MoistCabbage's Avatar
    MoistCabbage is offline Cadillac Owners 10000+ Posts
    Automobile(s): 2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
    Join Date
    Sep 2010
    East Boston MA.
    The current DEXRON transmission fluid is VI. Superior to and compatible with all previous formulations.
    mckellyb likes this.

  6. #5
    mckellyb is offline Cadillac Owners Enthusiast
    Automobile(s): 2005 STS N*, 1SF, 136K mi.
    Join Date
    Apr 2011
    Fort Worth

    Re: Transmission questions

    As someone who had a transmission cook itself at 113K miles, CHANGE THE FLUID!!!!

    DO NOT FLUSH!!!!

    Change, or have it changed, every 50K miles, it'll last longer.

    FWIW, you can put a drain fitting in the bottom of the pan, save the fluid, measure it, then use a small hand pump to put the correct amount of fresh fluid back in.

    I don't know if the access plug on the V6 is as inaccessible as it is on the V8, but if so, you pretty much cannot do it as Cadillac states, as it is supposed to be running and warm, however the fill plug is right next to the exhaust.

    I mean RIGHT NEXT TO.

    I had the minor burns to prove it, hence, drain plug added.

  7. #6
    atlrus is offline Cadillac Owners Fanatic
    Automobile(s): 04 escalade, 07 STS4 V8
    Join Date
    Oct 2009

    Re: Transmission questions

    Change ALL fluids as soon as you get the car, not only the transmission fluid - transfer case, differential, power steering, motor oil, etc.

    Not only will you have all fresh fluids, but if there are any issues - the mechanic will see them and alert you in time to avoid more serious trouble.

    Lot's of people complain about cracked rims, myself included (I think it's because of the suspension), so check them, too.

  8. #7
    Wojciech is offline Cadillac Owners Fanatic
    Automobile(s): Cadillac STS 3.6 DI 2009 RHD with Performance Pkg
    Join Date
    Feb 2014
    Southampton, UK
    Thread Starter

    Re: Transmission questions

    Thank you for your answer.
    I'm going change trans fluid asap.
    How many liter should I buy of Dexron VI?

  9. #8
    CadiTamer is offline Cadillac Owners Fanatic
    Automobile(s): 2006 STS 3.6 RWD
    Join Date
    Dec 2013

    Re: Transmission questions

    My car took 6 quarts, but that may be different. I'd get two gallons of the ACDelco Dexron VI with an ACDelco filter (Both can be had from the dealer, or from eBay, depending on what you'd rather do)

    While it is EXTREMELY difficult to change the fluid yourself due to the location of the fill plug, it is possible. The hardest part for me was getting the fill plug back in the transmission. I cheated, and dropped the back of the exhaust, and the back transmission mount to give me better access to the fill plug. The other option is to use a 1/4" wrench on a bit of the correct torx size. (T40 i think?) It's not a fun job, but with the back of the transmission and exhaust dropped, it's a TON easier than trying to do it with all the stuff mounted. Just be sure that even with the transmission dropped, it's still level, or you won't be able to get a correct reading on fluid level.
    Wojciech likes this.

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