T5 oil

Discussion in 'Classic Mustang Specific Tech' started by mustang70, Dec 21, 2004.


  1. mustang70

    mustang70 Founding Member

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    Would an 89 T-5 take ATF or gear oil? TIA.
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  2. mustangprodude

    mustangprodude New Member

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    ATF!!!!!! If you have the money use the GM Syncromesh synthetic fluid. It's like $8 a qrt. But from what I hear it makes a difference, especially on the shifting stuff. That's what I'm planning to put in my '00 GT T45 soon.
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  3. Hack

    Hack Active Member

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  4. BobV

    BobV Member

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    NEVER say NEVER. :D 83-84 Non-World Class T5's DO use 70W gear oil. Only WC T5's use ATF.
    LINKY
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  5. 6Stang7

    6Stang7 New Member

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    You just said it twice though.....:shrug:





    :D

    Anyone know what type of T-5 you could not use synthetic in? I though it was like the T-5Z or something because it had a carbon fiber piece that would disolve due to the synthetic oil. :shrug:
    #5
  6. Hack

    Hack Active Member

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    Ok, I guess the information I had was wrong. Link in post above.
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  7. ashford

    ashford Member

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    ive never seen a good t-5 with 80/w/90 in it . what i did with mine is i put in some limited slip additive to the atf. thats supposed to knock your gl rating up a notch. and dex3 has a gl rating of 1
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  8. 83GT289

    83GT289 New Member

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    yes yes. 83-84 non WC use 70W gear oil.
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  9. Hack

    Hack Active Member

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    Just received my Tremec T5 service manual.

    On page 2-1, it says:

    DO NOT USE GEAR OIL IN THE T5 TRANSMISSION SINCE THIS MAY DAMAGE THE BLOCKING RING MATERIAL.

    It's exactly like that in the manual, caps and all.
    #9
  10. 67coupestang

    67coupestang Founding Member

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    i use syncromesh in my tremec 3550 great stuff... expensive (especially if you forget to put the speedo gear back in and you puke it out) but smooth
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  11. BobV

    BobV Member

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    You didn't actually buy a manual, did you? The EXACT same service manual that vendors are "selling" is available for free online at :http://www.tremec.com/English/media/pdfs_autogen/T-5_Service_Manual.pdf

    And right above that line it says "Most T5 transmissions use Dextron fluid. Refer to vehicle owner's manual or service manual for specifications". When you go to the 83-84 Mustang 5.0 manual for NON-WORLD CLASS T5, it specifies 70W gear oil.

    Yes, I agree, MOST t5's use Dextron, but not all!!! :rolleyes: I've actually "been there, done that". :rolleyes:
    #11
  12. Darkhorse845

    Darkhorse845 Banned

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    Use Mobil 1 ATF it works great!
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  13. Hack

    Hack Active Member

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    Yes I did buy a manual. Good of you to post a link for the pdf version.

    The point I was making is that it's not as simple as WC uses Dextron and NWC uses gear oil. According to the manufacturer, gear oil can damage the transmission.
    #13
  14. 83GT289

    83GT289 New Member

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    83 84 non WC were not manufactured by Tremec. This makes your tremec manual irrelevant to these models of transmission. Tremec bought the T5 line from borg warner in 98. Yes, it is as simple as non WC T5 trans use gear oil and WC T5's use ATF. Borg warner produced the non WC T5's not Tremec.

    J.
    #14
  15. Hack

    Hack Active Member

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    Hmm, interesting that the manual is labeled T5 WC & NWC...

    And it includes separate sections for WC and NWC transmissions. Each section includes diagrams of all parts and separate assembly and disassembly instructions for each WC and NWC.
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  16. GypsyR

    GypsyR Founding Member

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    Try this, non-world class transmissions DON'T HAVE blocker rings. The manual includes blowup pictures of both. Note the carbon fiber rings on the WC but not on the non-WC.
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  17. Hack

    Hack Active Member

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    took me 10 seconds to find a diagram in the manual - page 7-5, figure 7-9 Assembly of T5 NWC Output Shaft Group. Item 73 - blocking ring.

    To make it clear, I believe that people should follow their manual as stated above. The service manual also says to follow your manual.
    #17
  18. mustang70

    mustang70 Founding Member

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    Man, I didn't realize a simple question would cause such a debate. I was asking for a buddy of mine with an 89 GT and figured I'd hit you guys up about it.
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  19. GypsyR

    GypsyR Founding Member

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    Ah, I see what you mean there Hack. I should have been more specific. I tend to think of those as the inner sychronizers. Funny that the parts list I order transmission parts from doesn't list them as "blocker rings" either. And unlike Tremec, they refer to the T5's as WC and non-WC where Tremec calls them STD and HD. I wonder if that manual is the same old Borg-Warner one or a newer Tremec version of it? Perhaps the parts supplier sells parts for such a variety of transmissions they are using their own terminology. Or maybe they are just sloppy. I don't know.
    Anyway I was actually thinking of the CARBON FIBER blocker rings that define the the most widelly recognized difference between a WC and non-WC.
    To further muddy the waters, we are currently running a WC with synthetic 5W-30 motor oil. It appears so far so good and it shifts more smoothly than a T5 using synthetic ATF. I can't recommend this as we haven't put enough miles on it for us to be sure the oil won't have any long term ill effects on the carbon fiber. The brass bits of the synchronizers tend to be just fine as long as they are getting some sort of lube or another. The carbon fiber we're not so sure about. We're applying knowledge gained from building racing transmissions for motorcycles here. What the manufacturer recommends may not be what works the very best. Though no one wants to run something that might compromise the transmission's longevity. Simplistically speaking, ATF is basically akin to 10W motor oil with a lot of detergent in it. So it's not a huge stretch to believe 5W-30 should work. Try it at your own risk. We do have a WC that has been on synthetic ATF since day one. It now has 167K trouble free miles on it and is still going strong. It's probably safe to suggest that seems to work pretty well.
    Umm,"The service manual also says to follow your manual". Does it now? Nevermind. I like debates. You never know when you might learn something.
    #19

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