flint54 Posted November 15, 2012 Share Posted November 15, 2012 Just passing on an observation. I recently replaced my clutch, and decided to try the Redline MTL fluid in the AX-15. Even though I've made it a habit to replace the gearbox oil every 10k or so, WOW what a difference! Much smoother shifting, very noticable difference. Link to comment Share on other sites More sharing options...
ftpiercecracker1 Posted November 15, 2012 Share Posted November 15, 2012 Good to know, I used a brand called Shaffers, crazy expensive, zero noticeable difference. :fs1: Link to comment Share on other sites More sharing options...
mountainman Posted November 15, 2012 Share Posted November 15, 2012 I'm with ya. Soon as i got my truck 2nd was very notchy when cold. Put in redline MTL and BAM... shes like butter. I fricken love that magic tranny soup. hehehe. AND you won't ever need to change again....;) That stuff has insane change intervals. We ran it in my moms jetta trans for 100k miles before we dumped it. Still looked like new. Link to comment Share on other sites More sharing options...
Mountain Dude Posted November 15, 2012 Share Posted November 15, 2012 What oil does the AX-15 normally use? I run the MTL in my NSG-370 in the TJ with good results and my MJ is supposed to use GL-5 (80W90) I was planning on changing it, but not sure if I want to spend the big bucks for MTL or Syncromesh. Link to comment Share on other sites More sharing options...
mvusse Posted November 16, 2012 Share Posted November 16, 2012 MJ transmissions (AX4/AX5/AX15) are supposed to use GL-3, not 5. GL-5 has a crapload of sulphur which is great for hypoid gears like in the front and rear diff, but it will eat the brass synchros in our transmissions. When GL-3 was being phased out, the specs changed to 10W30 motor oil as it is supposed to be about the same viscosity as 80W90 and has no sulphur. GL-4 has sulphur as well, but not as much as GL-5. Link to comment Share on other sites More sharing options...
flint54 Posted November 16, 2012 Author Share Posted November 16, 2012 RE: "not sure if I want to spend the big bucks for MTL..": Yeah, that was a difficult pill to swallow at $16/qt. Costly as Vegas showgirls. But, I figure if it prolongs the life of the box and has a much longer service interval, it may be actually cheaper in the long run. Link to comment Share on other sites More sharing options...
Mountain Dude Posted November 16, 2012 Share Posted November 16, 2012 Quote from the factory service manual I have: "Manual Transmission ....................... SAE 75W-90 API GL-5" Don't know what else to say... Link to comment Share on other sites More sharing options...
Geonovast Posted November 16, 2012 Share Posted November 16, 2012 MJ transmissions (AX4/AX5/AX15) are supposed to use GL-3, not 5. GL-5 has a crapload of sulphur which is great for hypoid gears like in the front and rear diff, but it will eat the brass synchros in our transmissions. When GL-3 was being phased out, the specs changed to 10W30 motor oil as it is supposed to be about the same viscosity as 80W90 and has no sulphur. GL-4 has sulphur as well, but not as much as GL-5. I don't remember which one's which, but the AX-15's synchros are not made out of the same material as the AX-4/5's. Link to comment Share on other sites More sharing options...
mvusse Posted November 16, 2012 Share Posted November 16, 2012 I know for a fact early and mid 90s AX4 and AX5 have brass synchros as I have had them apart and combined into one mostly good AX5. edit to add: It seems the early owners and service manuals erroneously listed GL-5, and was later fixed to read GL-3 for at least the AX4 and AX5. GL-4 is an upgrade to GL-3 and is good to use also (unlike I stated earlier). Supersede Chrysler part numbers now list motor oil as GL-3 is almost impossible to find anymore. Supposedly Redline MTL and MT90 and some other (Royal Purple, Amsoil?) are safe for brass also. The AX15 may have changed synchro material at some point during the mid 90s, but have not been able to verify this. Link to comment Share on other sites More sharing options...
RDAN1 Posted November 16, 2012 Share Posted November 16, 2012 There is a lot of discussion about this in other forums. I decided to go with synthetic 10w30 in mine. All is well and it shifts fine. Link to comment Share on other sites More sharing options...
terrawombat Posted November 16, 2012 Share Posted November 16, 2012 I know for a fact early and mid 90s AX4 and AX5 have brass synchros as I have had them apart and combined into one mostly good AX5. edit to add: It seems the early owners and service manuals erroneously listed GL-5, and was later fixed to read GL-3 for at least the AX4 and AX5. GL-4 is an upgrade to GL-3 and is good to use also (unlike I stated earlier). Supersede Chrysler part numbers now list motor oil as GL-3 is almost impossible to find anymore. Supposedly Redline MTL and MT90 and some other (Royal Purple, Amsoil?) are safe for brass also. The AX15 may have changed synchro material at some point during the mid 90s, but have not been able to verify this. I'm pretty sure Chryco issued a technical bulletin that says the listing of GL-5 fluid for certain transmissions was an error. Link to comment Share on other sites More sharing options...
mountainman Posted November 16, 2012 Share Posted November 16, 2012 Well for sure motor oil is NOT made to take the shear stresses that a trans puts on its fluid. So running motor oil is a FAIL on all levels and i wouldnt suggest it at any time. Just like honda states in their literature... use motor oil in the trans ONLY if man tran fluid is not available, and it is to be used for as short a duration as possible until man tran fluid can be put back in. Link to comment Share on other sites More sharing options...
RDAN1 Posted November 16, 2012 Share Posted November 16, 2012 Well for sure motor oil is NOT made to take the shear stresses that a trans puts on its fluid. So running motor oil is a FAIL on all levels and i wouldnt suggest it at any time. Just like honda states in their literature... use motor oil in the trans ONLY if man tran fluid is not available, and it is to be used for as short a duration as possible until man tran fluid can be put back in. Your Opinion and view is welcome but isn't shared evidently by Chrysler/Jeep who now recommend synthetic 10w30 for the ax15 since the gl3 lubes are no longer produced. As I mentioned in my post, there has been lots of discussion about this on other jeep forums and not everyone agrees. Link to comment Share on other sites More sharing options...
terrawombat Posted November 16, 2012 Share Posted November 16, 2012 Well for sure motor oil is NOT made to take the shear stresses that a trans puts on its fluid. So running motor oil is a FAIL on all levels and i wouldnt suggest it at any time. Just like honda states in their literature... use motor oil in the trans ONLY if man tran fluid is not available, and it is to be used for as short a duration as possible until man tran fluid can be put back in. Meh, it's not like manual trans fluid has some special formula that allows it to handle shear stresses better. It's just a heavier version of motor oil without as many detergents. Link to comment Share on other sites More sharing options...
flint54 Posted November 16, 2012 Author Share Posted November 16, 2012 I was rather surprised at the low viscosity of the MTL fluid. Poured quite a bit thinner than 10w30 motor oil. Link to comment Share on other sites More sharing options...
mvusse Posted November 16, 2012 Share Posted November 16, 2012 A lot of current manual transmissions use hypoid gears and need GL-5 to handle the sheer stresses of those gears. Neither the AX4, AX5 nor AX15 use hypoid gears. Link to comment Share on other sites More sharing options...
mountainman Posted November 17, 2012 Share Posted November 17, 2012 Your Opinion and view is welcome but isn't shared evidently by Chrysler/Jeep who now recommend synthetic 10w30 for the ax15 since the gl3 lubes are no longer produced. As I mentioned in my post, there has been lots of discussion about this on other jeep forums and not everyone agrees. Its because as was stated before, that they don't give 2 $#!&s about these cars anymore. If the trans was designed to use motor oil they would have started that way. But it was meant to use 80/90. A HUGE difference in every way from motor oil. Link to comment Share on other sites More sharing options...
mountainman Posted November 17, 2012 Share Posted November 17, 2012 Meh, it's not like manual trans fluid has some special formula that allows it to handle shear stresses better. It's just a heavier version of motor oil without as many detergents. .... :thwak: Link to comment Share on other sites More sharing options...
terrawombat Posted November 17, 2012 Share Posted November 17, 2012 Its because as was stated before, that they don't give 2 $#!&s about these cars anymore. If the trans was designed to use motor oil they would have started that way. But it was meant to use 80/90. A HUGE difference in every way from motor oil. It's heavier and it doesn't have detergents. What else am I missing? .... :thwak: I would love to hear the chemical differences between the two fluids. Understand that I'm not going to throw motor oil in every manual transmission & differential, but there are applications where it's perfectly acceptable. Chryco handed down a TSB stating such. You don't believe them and think they just don't care about our cars anymore. Knowing where TSBs come from and the process you must go through to generate one I can tell you that is not the case. Chryco is not the OEM of the AX-15...that would be Aisin-Warner and I'll wager a hefty amount that says they were included in the conversation of using motor oil in their transmissions due to the lack of availability of their original recommended fluid in North America. Now, with all that said - do I use motor oil in my transmission? Nope. I've had great success with a mixture of Redline MTL/MT90 in other, older transmissions so that's what I stuck with in my '92MJ. Link to comment Share on other sites More sharing options...
mountainman Posted November 18, 2012 Share Posted November 18, 2012 I could go on for pages about the differences but i tend to get sidetracked with pertinent info and my reply loses the punch it needs to make sense. So with todays people giving near ZERO credit to anyone they know who may know something and type it out, its easier to post a relevant article so readers can digest it at their pace and neutrally. Just the anti foaming properties alone that are needed in a manual trans is enough to negate the use of engine oil inside it..EVER. http://www.bestlubeusa.com/gearlube.pdf Link to comment Share on other sites More sharing options...
terrawombat Posted November 18, 2012 Share Posted November 18, 2012 That's a great article....written by the marketing group at Amsoil to try and sell you on their fancy and extremely expensive product. We can agree to disagree. There are far too many personal accounts and millions of miles that show synthetic 10W30 and the AX-4/5/15 go together like mustaches and pedophiles. Link to comment Share on other sites More sharing options...
mountainman Posted November 18, 2012 Share Posted November 18, 2012 Sounds good. Ill advise my clients and anyone who asks whats right and... despite the fact that you do the same in your rig.. you can... disagree? :hmm: Link to comment Share on other sites More sharing options...
mvusse Posted November 18, 2012 Share Posted November 18, 2012 Truth remains: 1 - conventional GL-3 and GL-4 do not exist anymore unless you pay $$$ to "boutique" companies. 2 - GL-5 will kill your brass synchros. 3 - 10W30 synthetic motor oil makes a better alternative to GL-3 than GL-5. I will trust the dealership and transmission manufacturer before an oil company's marketing department. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now