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synthetic Transmission Fluid? Are you using it? C70

My 98 C70 is due for its 100,000 mile tranmission service. I've been using standard tranny fluid for the life of the car, but I'm interested in changing to synthetic. Is anyone running synthetic and if so any advantages, disadvantages etc? Has it extended the life of the tranny.....

Also, is it better to flush or simply fill and replace the fluid. I'm afraid to flush it with the high mileage with all of the stories of tranny failures especially after flushing the tranny....

Any and all thoughts would be appreciated... Thanks.








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    synthetic Transmission Fluid? Are you using it? C70

    Have AMSOIL synthetic ATF in my daughter's 850 turbo. The shop where she bought it put it in--they didn't use a flush machine, but did change all the fluid.
    If you don't feel comfortable changing it all yourself, you can change what is in the pan 3 or 4 times, and have mostly synthetic in there.

    While Dexron may be "overengineered", GM has found it necessary to upgrade the specs because a lot of them out there don't protect well enough.
    The synthetic ATF will resist oxidation, run cooler, pump better in cold, and reduce wear. It can be used for three times the normal service interval (and will probably still test as useable for continued use.








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    synthetic Transmission Fluid? Are you using it? C70

    Dexron is the most over-engineered fluid in your car. I'd replace the air in my tires with pure nitrogen before I'd worry about switching to synthetic ATF, which can never return more than a fraction of the benefits that can be gained by switching to a synthetic engine oil (which is subjected to combustion byproducts and excessive temperatures, and also expected to remain as slippery as possible).

    For most applications, synthetic ATF is a total waste of money, though it might be good for your peace of mind iff you regularly use your passenger car to do a lot of heavy trailer towing in hilly terrain in high heat under stop-and-go conditions.

    I let my AT flush it's own Dexron ATF (with more of the same) at 61K miles after much heavy use. That's the only maintenance it's had, and it's still going strong. I owe the car a timing belt; I may do the flush ritual again at that time for the hell of it.

    I am wary of "flush machines" (nevermind their chemical treatments!), and consider draining/refilling to be worse than no maintenance at all.

    After suddenly switching the fluid from well-used to new, its "grabbiness" factor will suddenly change. Rather than have the AT figure this out from new experiences, better to pull the AT's ECU's fuse for a while and then have the AT start out in learning mode with the new fluid.

    My hunch is that most of the horror stories you've heard are not only broadcast way out of proportion to the happy stores that were never told, but involved cases in which there was already a transmission malfunction that had chewed up the old ATF, so, unsurprisingly, flushing the ATF did not help the situation, any more than a blood transfusion can cure someone who's suffering from leukemia.

    - Dave; '95 854T, 143K mi








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    synthetic Transmission Fluid? Are you using it? 850 1995

    I do the tranny fluid flush myself every 30k miles with Mobil 1 ATF (synthetic). Another person : Ken Temkin, http://www.brickboard.com/AWD/?id=644475 posted the most likely reason why the high mileage tranny has problem after flushing.

    If your tranny is similar to what Ken described, drain & replace the fluid would take a bit longer to reveal the tranny problem while flushing would reveal the problem much sooner.

    Ching-Ho Cheng
    --
    1995 855 NA, Bilstein Shocks, K&N Filter, E-Code Lens, Apline CD-Changer







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