Synthetic ATF for a '99 Olds Intrigue?

Planning to change ATF & filter in '99 Intrigue 3.8L 153K. It's never been changed, shifts fine and no burnt smell. Considering upgrading to synthetic - what do you recommend? Is syn overkill? Is there an additive I should use prior to ATF change (cleaning)?
 
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10,008
Location
Upstate NY
Syn ATF is not overkill, not if you want the transmission to last a while longer. Dex-VI also works well, and is rumored to be part-syn. What I'd do right now is drain the pan, re-fill with some cheap ATF, run it a week or two, change it again, add Auto-RX and follow the directions, then drop the pan, change the filter, and flush with the full synthetic ATF. This worked wonders for my Buick LeSabre's transmission. My reasoning is to get some of the cruddy old fluid out, clean the transmission up a bit, then hit it with all-new fluid. Kinda like changing the water in a fishtank. You don't want to change dirty water all at once, otherwise you'll kill the fish with the clean water they're not used to.
 

JHZR2

Staff member
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44,841
Location
New Jersey
Run Dexron VI - it is a great ATF, designed exactly for your application, and is syn at least to the extent necessary to provide excellent performance!
 
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8,756
Location
RI
No additives or double flushing needed ever. Just change it with the ATF of your choice. Any full synthetic, like Amsoil, Redline, Mobil1, Royalpurple, Amalie,.... or any DexronVI will do you well. Syn is never overkill.
 
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1,445
Location
Grand Rapids, MI
I'd use Dex VI or one of the others that unDummy recommended, whatever you find cheapest or easiest. Any will work. A pan drop will get out around 70% of the fluid if I recall. My 4T60E and 4T65E both took about 7+ quarts with a pan drop and filter change. I'm using GM Vehicle Care Dex VI in both my vehicles.
 
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6,388
Location
Washington St.
Cleaning the transmission with Auto-Rx isn't the use of an additive. It cleans the years of crud and varnish and reconditions the seals. I've seen it work very well on old engines and transmissions. Highly recommended. http://www.auto-rx.com/auto-rxnet/index.html Any Dexron-VI ATF will do an excellent job, as will any ATF made to meet the old Dexron-III spec. Your choice. The Dexron-VI is a more robust fluid.
 
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1,034
Location
GA, USA
I've done several d&fs on our '01 Intrigue (4T65E) so it has a mix of M1 ATF, Redline D4 ATF and Royal Purple MaxATF. Trans shifts great.
 
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