NDFORSPD

I know on my Borg Warner that the side of the trans case says to use dexron 3. I am having a ton of trouble finding a good quality dex3 at this point since now everything has turned to dex 6. What is everyone using? I'd prefer to stay with dex3 as there is rumor that dex6 harms the paper blockers. Is this true? I would like to change out the 6 y/o fluid as it has low milage but it has been in there a while.

dailydriver

I don't know about it harming the blockers, but it IS way too thin for our T56es, unless you live in upstate Alaska, or such.

Firebrian

When I did my 1999 T56 fluid change 3 years ago I used Valvoline Dex III/Mercon. I'm pretty sure when I changed my fluid it was 13 years old with 12K miles on it. I noticed no obvious difference in the shift quality with the old or new fluid in. I had the same concern for the paper blocker rings. Would be surprised that a decent Dex III is hard to find with so many 15 year old cars still on the road. Amazon for one carries it. As of 3 years ago Tremec recommended either Dex 3 or Mobil 1 synthetic ATF.....based on actual test results. Note, they didn't test all the other synthetic or auto ATF choices either....hence no recommendations. I felt more comfortable with the non-synthetic on my paper blocker rings based on the voluminous feedback of users of each type. There are dozens of pages on this site about this topic over the past 10-15 years.

https://ls1tech.com/forums/search.php?searchid=28321493

Castrol, Valvoline, Advance Auto Parts ATF, GM 88861800 (ATF for manual trans), etc. will all work. Dex 6 is backwards compatible for automatic transmissions....though probably not for an ATF being used in a manual transmission.