T-5 transmission

flathead4rd

flathead4rd

Well-known member
What type of transmission fluid do you use in your T-5. I've been running automatic trans fluid in mine as recommend by the re builder.
 
Been selling rebuilt S 10 T-5 transmissions for 20+ years and the rebuilder I use puts a tag on the trans recommending Dexron III. I've also used the GM recommended fluid available thru GM parts. Problem with regular gear oil is if you live in an area where it gets cold the gear oil can thicken and make the trans shift hard.
 
I was a mechanic for the phone company (GTE/Verizon) for 30-years. We bought another phone company that had S10s in their fleet with T-5 transmissions. They all had ATF in them. We didn't have any manuals on them. So, we were told to get that ATF out of there and put 90W gear oil in. They had a gas station servicing them and we thought they had made a mistake. We rebuilt manual transmission for years and I never saw one that used ATF. Guess what, they would not shift with 90W gear oil in them. You'd go to shift it and the synchro acted like it hit a steel wall and it would not go into gear, it wouldn't grind, it would not go into any gear while moving. Drained the gear oil out and put ATF back in it and that fixed it, it nicely shifted again. We finally found the specs on them and sure enough they used ATF, automatic trans fluid. I had a few of those transmission apart over the years and I looked at them hard and I still could not see why they would not work with the gear oil, the synchro's and gears looked the same as any other trans. The only thing I could think of was maybe they had tight tolerances on them. To answer your question, I would put whatever was in that trans originally. I don't know if all T-5 transmissions use ATF but the ones we had did.
 
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What means "World Class" & " Non World Class "? Are these different transmissions or are the internal specs tighter?
I have seen the terms here on the Barn, but not the reason for the terminology. JP
 
I'm new at this, but somewhere around '93-'94 Borg Warner went to the 'World Class' transmissions as Detroit was ramping up the hp in mustangs, camaros,chargers etc. The transmissioin was beefed up to suit this with a different configuration in the bearings and different type of synchros which may have had some kevlar or carbon fiber involved. With the bellhousing removed, one can easily identify if it is WC or pre WC by a bearing race that has a concave or some shape. That is a brief overview and much has been written on the subject by actual experts if you were to search for it online. As for the fluid I use in my WC, I used Amsoil's synthetic 'dexron III', because a neighbor gave me a gallon jug of it a few years ago when he moved. Shifts like a dream.
 
GB always has the logical answer, " because my neighbor gave me a gallon jug".
Same thing I would have done to rid the jug from my shelf. I am normally not a big fan of
synthetic oils, but modern trannys seem to like it. I run 10-30 synthetic in my old diesel dodge ******, way to light for my way of thinking, but thats what the factory shop manual recommends, and all the high mile guys run the synthetic version.
 
rAN A fORD mUSTANG t-5 FOR OVER 20 YEARS WITH atf IN IT. aT PRESENT i WAS RUNNING A t1020 AND i THIN K THAT ALSO RUNS atf. i THINK THAT TRANS IS BETTER THAN THE t-5 IN A STREET ENGINR,
 
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