Author Topic: fluid nchange  (Read 1572 times)

Offline Smitty31

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  • 1979 GMC High Siera 4wd & 1986 custom deluxe 2wd
fluid nchange
« on: October 13, 2017, 07:22:43 PM »
I have owned my 1986 4.3L 4 bbl 400 turbo trans 2wd for a year. I have never changed the transmission fluid and have no idea when the previous owner did last. Currently it shifts smoothly and does not slip. It had been leaking fluid around the rear seal and the silver bullet at the speedometer. I replaced seals and O-ring and now no leaks. Is there any real proof that changing the transmission fluid and filter after 100,000 miles is hard on the transmission or even cause it to go out. I always figured it did not because a lot of people waited till the transmission was already slipping or having other problems before they changed filter and fluid. I would like facts not opinion and see if this is myth or fact.
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Offline Stewart G Griffin

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Re: fluid nchange
« Reply #1 on: October 13, 2017, 11:58:52 PM »
It's funny you ask this because i was planning on changing my trans fluid tomorrow (actually this morning at this point).    And i've had the truck since 06 and have NEVER changed it!   

i was starting to do research tonight but am too sleepy to continue, will do more tomorrow, but here's a start:

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2202175


Offline VileZambonie

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Re: fluid change
« Reply #2 on: October 14, 2017, 06:36:13 AM »
What it stems from is the customer who neglected their vehicle, especially their transmission and when symptoms would arise they would request the fluid and filter changed. Subsequently it accelerated the failure and the customer would blame the garage, so garages became wise to this and started questioning, advising and documenting before simply performing the service. Generally speaking if there aren't any issues you should be fine changing the fluid and filter without adverse effects, prolonging the life and performance of the transmission. If a transmission begins slipping and you then change the fluid you essentially will increase the rate at which it will ultimately fail. The gunk may be helping aid in what friction remains in clutch packs that are near failure.
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Offline Smitty31

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  • 1979 GMC High Siera 4wd & 1986 custom deluxe 2wd
Re: fluid nchange
« Reply #3 on: October 14, 2017, 10:25:52 AM »
That's how I felt about it but wanted to be sure. Thanks for the input. Smitty31
IF ITS WORTH DOING. THEN ITS WORTH DOING RIGHT.