Using High Mileage ATF in low mile tranny?????

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Would it be good to use High Mileage ATF in a low mileage transmission? What does the HM ATF fluid have, besides seal conditioners, that helps the older (or newer) trannies? I have been using 1 quart of HM with 3 quarts of standard ATF to refill my pan after I drain the old fluid (no filter change). it's a GM 4L60E tranny. the bottle of HM says it has an enhanced additive package including seal conditioners and shear stable modifiers. And improves and maintains smother shifting longer than conventional ATF fluid.
 
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I think it is a bad idea, I have 372,000 miles on a Turbo 350 transmission and I am using Amsoil ATF.
 

Loobed

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why is it bad? i was thinking that maybe the seal conditioners would weaken the newer seals, but one quart wouldn't hurt, thats why I didn't use 4 quarts to refill the tranny.
 

JHZR2

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the bigger question is why do you need it? Unlike a HM oil, where one may never replace an oil pan gasket or rear main seal, in an AT, the main seal, the pan gasket, typically is changed every time you drop the pan and replace the filter, you replace the gasket. So conditioning a throwaway seal seems like a silly thing to do. Extra detergents and a slightly higher viscosity is a smarter thing to do, though Id be more interested in choosing a more stable AT... so I'd be looking to get Dexron VI in there first and foremost...
 
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Stick with the standard juice. The HM attributes are not going to be utilized in your unit. Not sure if you are into synthetic ATF or believe in it but that would be your best choice here. Dex VI is also another good choice unless you are on the DEX III or else band wagon Your trans does not leak, probably shifts like a dream so no improvement will be noted with the HM formula. Go with something else when you drain it again. In the meantime atleast it wont hurt anything!
 

Loobed

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I will eventually run the Dex 6. A Dex 6 flush would be a little more than I want to spend. with filter and gasket, it would be under $100. I do not have 100% HM fluid. Maybe 15% HM and 85% standard Dex-III
 

PT1

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 Originally Posted By: unDummy
HM ATF will fine in any age transmission. The attributes are "marketing".
+1 do the HM no problem
 
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 Originally Posted By: unDummy
HM ATF will fine in any age transmission. The attributes are "marketing".
Again, unDummy the voice of reason on this site...
 
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Man did you guys just become best friends! I disagree, a HM ATF has different additives than regular old DEXRON III. They are not needed in a new trans. But im sure unDummy appreciates the compliments and your admiration of him and his always correct opinions.
 
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