4 Speed Owners Must Read!!!!!

Discussion in 'U-shift em' started by bostongsx, Mar 16, 2009.

  1. Todd69GS

    Todd69GS Silver Level contributor

    Couple things to check Tim. First check the adjustment on your shifter to be sure that fourth gear is engaging properly. If that seems ok then I would say that the synchro is worn and is not holding on anymore. Another possibility is the shift fork is severly worn down and is not pushing the slider up far enough. Often the shift fork will wear down when someone is driving with their hand resting on the shifter while it is in fourth gear. This can cause the fork to ride on the slider and wear out both the slider and the fork. Sounds like it may be time for a freshen up.
  2. PaulGS

    PaulGS Well-Known Member

    I have used that for a few years. Works great.
  3. Aerobatix

    Aerobatix Well-Known Member

    Oh boy!!

    I recently changed fluids in both my Muncie and the rear-end with Valvoline gear oil. Bought it at the local AutoZone. I added the corect GM posi fluid to the rear-end and used it straight in the Muncie. I have about 150 miles on the car since changing fluids.

    I read this post and go out to check the Valvoline bottles and sure enough.....it says GL5 on the rear of the bottle. So, do I simply drain both and refill with a correct GL4 fluid, or do I need to flush each with something?

    I'm thankful for the board and people sharing info as I would have never even thought this could be a problem. I hope I haven't caused any harm with 150-200 miles with the GL5 fluids.

    So, flush or simply refill?



    Attached Files:

  4. Lee Bacon

    Lee Bacon Well-Known Member

    Good question Rob as I just did the same thing!!!!! CRAP
  5. moleary

    moleary GOD Bless America

    going Redline with my project:TU:
  6. LUV455

    LUV455 455 LUV Truck

    I have been using Bel-Ray motorcycle transmission 85 wt in my ST10 and has no problems have used it for years now i have to go read the label and check.
    Oh well it has saved a bunch of T-5s as well.
    Thanks for the info.
  7. Lee Bacon

    Lee Bacon Well-Known Member

    Royal Purple Syn has GL-5 & GL-4 on the bottle. Is it safe? There Coastal brand has GL-5, GL-4 & GL-3 on there bottle. How about this? These lubes are at Advance Auto part's.
  8. bostongsx

    bostongsx Platinum Level Contributor

    No Not Safe

    Gl-4 Only
  9. Lee Bacon

    Lee Bacon Well-Known Member

    Herb i've been all over & even had several part's managers try to find GL-4 only & can only get it in 140 wt, Now What?????????????
  10. bostongsx

    bostongsx Platinum Level Contributor

    Order redline mtl from summit, jegs, or you local speed shop
  11. Aerobatix

    Aerobatix Well-Known Member

    OK - I just called and spoke with a tech at Red Line. I asked specifically about the GL4 & GL5 ratings as related to older muscle cars and asked about MUNCIE transmissions and the rear differentials as well.

    I mentioned that I had read the GL5 would cause problems in the older muscle car equipment with corrosion and wear on synchros and clutch packs. He stated that most common brand GL5 fluids do contain certain chemical additives (phosphates and sulphurs) that will cause issues with synchros and clutch packs. Red Line DOES NOT contain these chemical additives and is SAFE for use in Muncies and Rear Diffs.

    I ordered 2 quarts of each fluid for my tranny and diff. Cost from Summit was $53 delivered.

    Hope this is helpful info!


    I asked which specific fluids to use in a Muncie Transmission and was told to use :

    75W90 NS
    This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin.

    I asked which specific fluids to use in a Rear Differential and was told to use :

    Our most popular gear oil, this is the preferred product in nearly all car and light truck differentials, both conventional and limited-slip. 75W90 is preferred for most racing applications. It contains friction modifier which is recommended for limited-slip units. 75W90 Gear Oil can be used in many transmissions and transaxles; however, other Red Line lubricants have better frictional properties for rapid synchronization. Exceeds API GL-5.

    Attached Files:

  12. PaulGS

    PaulGS Well-Known Member

    The only gear oil I found to be GL-4 was Amsoil.

    The bottle says made for Muncie, Top Loader, etc.

    DO NOT USE GL-5. The additive in it reacts with brass at evelvated tempretures, and corrodes them.
  13. MPRY1

    MPRY1 Gear Banger

    Anyone try Penzoil Syncromesh fluid? Supposedly not GL rated, but has a viscosity near 80W. The only place I have seen it sold is Murry's / O'reillys. I have read its compatible with older transmissions but would like some opinions before I drain and fill my M-20.
  14. Lee Bacon

    Lee Bacon Well-Known Member

    Hey Guy's, I drained my M-21 of Valvoline Gl-5 & ordered MT-75-90 Redline like Rob said from Jegs (but got 4 quart's) for 53.00 del. Put it in & as I shifted into reverse I could tell a diff. right away, went a couple of blocks & It felt like I just had the tranny & shifter rebuilt!!! WOW what a change!! Don't mess around guy's Get Redline!!!!!!!!!!!!!! Thank's Rob & don't forget to look close @ bolt # 5 close to the wachamagiggy next to the thingamaggy, I think it has the wrong anchor on it:laugh: :laugh: :laugh: :laugh: Had a Great time meeting you at BPG & You have a REALLY nice X, :TU: buddy-----Lee:beers2:
  15. Aerobatix

    Aerobatix Well-Known Member


    Glad to hear the gear fluid change had good results.

    I am on the hunt for the correct doohickey whatchamacallit and #5 screw/bolt with captured castillated star washer. :Dou:

    Good to have met you and looking forward to next time!

  16. bostongsx

    bostongsx Platinum Level Contributor

    I am glad we found this out before it hurt our trannys
  17. Lee Bacon

    Lee Bacon Well-Known Member

    Keep looking Rob!!! it's under there somewhere:laugh: :laugh: :TU: See you next time! :beer
  18. kiddsixpack

    kiddsixpack Active Member

    I am so glad I recently joined this forum, It's tips like this that save major Time and Money.
    thanks again
  19. Jclstrike

    Jclstrike Well-Known Member

    Just curious if anybody is familiar with 5speeds dot com? its says(post by Paul of Medatronic Corp):

    If I may shed some light on the war. After seeing thousands of Muncies this whole GL5 - GL4 thing is some marketing hype nonsense put on by the synth manufacturers to justify the overpriced crap they are selling. I've never seen any rings ever corroded. Nor have I seen thrust washers, and bushing fall apart because of the CORROSIVE EFFECT of the GL5!

    That being said, most people here will not push their transmissions to the extreme temps that synths offer better protection with.

    Consider this. Where extreme conditions exist, be it cold or high heat during a Nascar race, synths have some merit. However having dealt with every manufacturer that makes transmissions for Nascar, NONE use or recommend the common hyped up stuff you see advertized in your favorite mag. Synchros are not an issue, since these race transmissions don't have them. What is paramount, is protection (the gears) from heat checking and galling. Your Red Lines and Amsoils fail at that. Sorry, but the big boys may use these "popular oils" in engines but rarely in gear boxes. Please I know some guy is going to respond with the "my box runs XXXX, and it works great", good for you, bravo.

    However I have documented that the Royal Purple Max Gear and Mobil One gear lubes work quite well on the track and shifting is fine on fairly concentric synchro rings.

    Once a ring is egg shaped from being overheated, a thinner oil can help. So a tired worn synchro ring may come to life with the use of GM Synchromesh fluid. Yes, you can use it in a ST10 or Muncie, but the Muncie may leak more.

    If you're happy with what works for you, keep in mind it may not work for others because the most critical component that people base their oil wars on is how a unit shifts. Older transmissions with worn rings may react better to some oils or become problematic yet with others.

    I have seen more shifting issues decline rather than improve with the use of Synth oils and in fact have seen synchros crack in race application because the rings where skidding on the gear cones, vibrating and coming apart..... again racing.

    I think I see army tanks coming.... I'm outta here...


    Any Thoughts?
  20. buick64203

    buick64203 Just plum crazy Staff Member

    For those of you that are on the hunt for GL-4 gear oil and cant find it, my local NAPA stocks it in 1 gallon bottles. Made by Sta-Lube. It is GL-4 specific. So if anyone needs it, try your local NAPA. :beer

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