4L60E "Shouldn`t change the transmission fluid"???

Discussion in 'The "Juice Box"' started by STAGE III, Jan 13, 2021.


    STAGE III Lost Experimental Block

    So our 97 year old Mom is ringing my phone off the hook to get her 92 Roadmaster back on the road safely (ummm lil contradictory? 97 year old driving a car safely? Lol). Just using it for grocery store runs (after Covid of course) and the all important hair dresser.

    Well, she is sharp as a tack, takes ZERO meds & can walk circles around me at grocery store lol

    I installed a new battery in her car yesterday,topped off the leaking transmission (3 1/2 quarts) test drove it
    (with her smiling ear to ear in dove leather passenger seat : ) and then dry-rited the transmission fluid leak.

    SHE INSISTED I not do the job so called up the local service manager and the guy tells me "an old timer had told him never to change the transmission fluid unless you wanted problems,which he did in his car anyway and it screwed it up so he wouldn't recommend it".

    I told him it definitely needs a pan gasket or dipstick O-ring (changing fluid on its own! Lol). Plus it is an 11 quart system anyway on the 4L60E and the torque converter has no drain provisions anyway so will only lose 5 quarts anyway putting a new filter & gaskets in it.

    What does this line of thinking recommend refilling the trans with the contents of the catch pan?

    Anyhow juuuuuuust asking in case I missed some secret tranny (heh heh I said "tranny") dark magic to prolong the transmission life?


  2. Max Damage

    Max Damage Well-Known Member

    Maybe it's just another version of "If it ain't broke, don't fix it?"

    Might make me go to another mechanic...
    bostoncat68 and STAGE III like this.
  3. JoeBlog

    JoeBlog Platinum Level Contributor

    Different trans, but my 06 Pontiac has a “filled and forget it” transmission. It’s supposed to get a fluid exchange at 120K, which is almost here. I’ve been told by a few GM mechanics NOT to do it unless there are issues, and unless I want issues, to leave the fluid alone. It doesn’t leak (probably can’t; 0-ring gaskets better than compressed rubber or cork), and shifts perfectly, so I’m just keeping an eye on the fluid level. Maybe there’s some teeth in that rumor.
    STAGE III likes this.
  4. 6769RIV

    6769RIV Platinum Level Contributor

    Subscribed. Hopefully a builder / OEM engineer type will weigh in, specifically for this transmission. Have heard a lot of the same things for different makes models and years, as well as the old "every 20K filter and fluid change" stand-by.

    That said, 3 1/2 quarts is a lot. You've effectively replaced half or most of the fluid already just topping it off. :D
    STAGE III likes this.
  5. Luxus

    Luxus Gold Level Contributor

    I have never heard of never ever changing the trans fluid. Yes they can go a long time without needing a change, but I can't see how a fluid change would do anything bad. Only two scenarios I could think of that could cause problems. They used full synthetic instead the normal and then I think it would only cause leaks. Or the trans was in bad shape to begin with and new fluid (with new detergent) broke a bunch of gunk loose that trashed it.

    Just my 2 cents, I know there are way more knowledgeable trans guys here, hopefully they will chime in.
    STAGE III and 6769RIV like this.
  6. Max Damage

    Max Damage Well-Known Member

    Here is a somewhat annoying Youtube guy:

    Basically, he explains this means the transmission should have had the fluid changed much earlier. Due to the fact that the manufacturers recommendation left the dirty fluid in too long, the dirty fluid is now creating additional friction in the torque convertor, which is keeping it working.

    Personally I think you should change the fluid and if that reveals a problem with the transmission, so be it.
  7. buicksWILD

    buicksWILD Well-Known Member

    I personally never do a flush. I've always just dropped the pan and replaced the filter instead. When I was at a chevy house the transmission guy would recommend a flush when people came in complaining about transmission issues. He told me that flushes usually make the issue worse and that was his way of securing a rebuild.
    sean Buick 76 and 6769RIV like this.
  8. Matt69olds

    Matt69olds Well-Known Member

    That is one of the oldest and most stupid myths I have ever heard. I really wish it would go away. It REALLY like to know how the myth got started!!

    I bet the myth started with someone who had a transmission that wasn’t performing as expected. It either slipped, delayed engagement, or some other concern. Guy figures “hey, I haven’t ever changed the fluid or filter” so proceeds to change a filter clogged with clutch and band debris. Then pours a couple quarts of fresh fluid, diluting it with 7 quarts of nasty burnt fluid. Needless to say, this fixes NOTHING. When the transmission completely fails a few weeks later it’s obviously because of the new fluid and filter.

    I have heard all the arguments. Feel free to pick one, or add to the list.

    The transmission needs the grit so things won’t slip. (The friction material is SUPPOSED to be on the clutches a d bands, not in the fluid!!)

    The detergents in new fluid will loosen up deposits. If there is so much crud hiding in crevices that the new fluid loosened them up, you had problems LONG ago!!

    New fluid will cause leaks!!! Why doesn’t that happen after oil changes???

    If it ain’t broke, don’t fix it!!! Good idea, leave the hood closed until the engine won’t run, then do the long overdue maintenance!!!

    Changing the fluid or filter should never be considered a repair. If changing the filter fixes anything, the transmission was on borrowed time anyway. Transmission filter/fluid change is best thought of as maintenance.

    My 06 Ram Diesel has 200k, I changed the fluid and filter and adjust the bands once a year. People always ask how many transmissions have been installed in the truck, I reply with my usual smart ass answer “including the factory transmission? Just one.” Even with some performance upgrades, there is never more than a very slight amount of debris. Typical end result of clutch and thrust washer wear.

    Bottom line, if the transmission works as is, other than a leak, changing the filter and gasket isn’t going to cause problems.
  9. Matt69olds

    Matt69olds Well-Known Member

    The only proper way to flush a transmission is to disconnect the return cooler line from the radiator. Connect a hose to the radiator fitting, put the other end of the hose in a bucket. Have a helper start the engine, as fluid is pumped out of the transmission, add more thru the filler neck. Eventually you will see fresh new fluid coming out of the hose. At that point, all the old fluid from the converter, cooler lines, and transmission cooler Ahmad been cleaned out. At this point change the filter and refill.
    Last edited: Jan 13, 2021
  10. 6769RIV

    6769RIV Platinum Level Contributor

    Just curious how many miles are on the car (transmission)?

    STAGE III Lost Experimental Block

    Just turned 100k, I am sure when my Dad was alive he had it changed at the appropriate time, as he loved that car.
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I bought my 98 Riviera in 2004 with 86,000 miles. I immediately changed the trans fluid, and have done so every 20,000 miles, the last 2 or 3 times, I have used Valvoline Max Life ATF which is fully synthetic Dex 6. The car now has a bit over 200,000 miles on the original transmission, which does not leak, and shifts perfectly. I agree with Matt, that is a myth about not changing fluid on a high mileage car. Synthetic fluid withstands heat much better. Switching to it might cause seeping or leaks, but it won't hurt the transmission. Dex6 is the best ATF yet, and is completely backwards compatible.
  13. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    This is an old one. Most folks never b.c. think of their transmission fluid or filter until the trans starts to act up. So they swap the filter and fluid hoping for a miracle.. go figure the trans goes shortly after.
    STAGE III likes this.
  14. Ryans-GSX

    Ryans-GSX Have fun, life is short.

    John at 100k you can change the fluid and most likely won't have any problems. If your really worried about it you can catch it and put it back in but I don't truly believe you will have any kind of problem at 100k. I would say go back with the regular dextron fluid don't change over to the synthetic fluid or any kind of newer formula.
    STAGE III likes this.

    STAGE III Lost Experimental Block

    Appreciate it gentlemen,will get it fixed up tomorrow and most importantly fix that leak not only for the car but for Mom as it had spread out from under the car exactly to where she steps going into the car (I already policed that up).
    Don’t want her falling in the garage.
    Then I am going to detail it for her,which will make her even happier!
    : )

    BRUCE ROE Well-Known Member

    My opinion, some kind of regular filter change is more important. That process could
    reveal other problems developing. Of course you are only changing some of the fluid
    each time, with much remaining in the torque converter.

    The seals that keep fluid inside the case are not the ones you need to be much concerned
    with. The seals on the edge of clutch pistons need to hold a lot of pressure to engage the
    clutches. When they do not, the clutch could start slipping, burn up, and poison
    everything, what a stinking mess that is.

    All my TH400s have a drain plug brazed and tapped into the cover. Bruce Roe
  17. black70buick

    black70buick Well-Known Member

    From the lead GM Turbo Hydromatic engineer I bought my 4L80e from. Don't change the transmission fluid unless there is an issue discovered like a leak, burnt fluid and the like. Otherwise the newer THM generation (circ mid 90s) transmissions are designed for high milage, low wear to the point that fluid and filter changes are not necessary. If you have increased the power plant output significantly beyond the nominal average power range of the transmission then additional matenance considerations should be made. Likewise vehicle model and application influence maintenance and this normally applies to 1ton + trucks. Most THM applications are light duty passenger trucks and cars. This is the correct clear explanation. There is no opinion here. If the car is stock, barring any detected issues leave the transmission alone hence no drain plug. Follow the maintenance schedule prescribed for the vehicle application irt the transmission. Obviously to the original poster's concern, low fluid forces a matenance inspection and service.
  18. Max Damage

    Max Damage Well-Known Member

    It’s the opinion of someone who expects the transmission to run a long time without issue, and then be rebuilt or replaced.

    It’s not the opinion of someone who wants to maximize the service life of the new unit. That would require more regular maintenance.

    Pick your poison.
  19. 72gs4spd

    72gs4spd Well-Known Member

    I have a 2000 Yukon XL with 200K original transmission. When I bought it had 50K. I drained the pan every 3 oil change used mobile synthetic atf and changed the filter every two years along with transfer case oil and front and rear diff lube. Never had an issue no leaks either to this day. Uses maybe a qt of oil between oil changes. Maintenance is always key to longevity.
    Max Damage likes this.
  20. GS464

    GS464 Hopelessly Addicted

    Our fleet of E-450 and F-550 shuttle buses are serviced on the factory schedule using factory filters and Valvoline MaxLife every 60k. It's been normal to see 350k up to 500k on the factory transmission. Our vehicles each run 100k to 135k annually. We rarely have transmission failures and none have been due to simply worn out. The last two have been due to solenoids that went bad, burning out clutch material and sending bits through the system.
    Based on my experience, service a stock trans properly for the longest life.
    Max Damage likes this.

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