crumbscomanche Posted July 1, 2017 Share Posted July 1, 2017 Good afternoon everyone, I am trying to ID my transmission so I can do a fluid change as a part of new ownership maintenance. I don't think the tranny of t-case fluid has been changed in the last 200k miles, since the engine and transmission were rebuilt. My understanding is that 4.0s only came with AX-15- can anyone confirm this? If so, would anyone be able to provide a link to the proper fluid? I've read that Redline is good stuff and will not ruin the synchros. Any help would be much appreciated. Thank you, and happy Fourth! :USAflag: Link to comment Share on other sites More sharing options...
Pete M Posted July 1, 2017 Share Posted July 1, 2017 87-89.5 4.0l MJ had the peugeot manual. 89.5-92 4.0l MJ would have the ax-15 manual. Link to comment Share on other sites More sharing options...
MuddFoot Posted July 1, 2017 Share Posted July 1, 2017 Also he didn't specify auto or manual so could be aw4 Sent from my Z981 using Tapatalk Link to comment Share on other sites More sharing options...
crumbscomanche Posted July 1, 2017 Author Share Posted July 1, 2017 Thank you, Pete. I appreciate the quick response. It's a 1991 5-Speed, so it sounds like I have the AX15. Is Redline the way to go for the fluid change? Do you happen to know what weight I'd want to go with? Link to comment Share on other sites More sharing options...
Comanchakazie Posted July 1, 2017 Share Posted July 1, 2017 Is there any way to tell physically which transmission one has? Or is it safe to assume my '90 4.0 manual is AX-15? Link to comment Share on other sites More sharing options...
DirtyComanche Posted July 1, 2017 Share Posted July 1, 2017 There's probably as many opinions on fluid to use as there is members of this forum. You're supposed to use an API GL-4 oil according to the OEM, but that is an obsolete standard. Chrysler later decided that 10w30 motor oil (IIRC) was acceptable. I used Lucas 75w140 Synthetic last time. It is a API GL-5 oil, and is listed to exceed the requirements of a API GL-4 oil. But it might eat the synchos, although technically it shouldn't as if it exceeds the GL-4 spec. Personally I doubt it will and feel that was something of an overblown issue to begin with, probably exaggerated by the formulation of the early GL-5 oils that were quite likely to corrode yellow metals. There's lots of AX-15s running around with the cheapest 80w90 that the quick lube pumped into them, and failures are rare. A better oil might have been the Redline MT-90 75w90. I can't buy it easily, so I wouldn't. Amsoil MTG would probably be the best option, but it's quite pricey. Royal Purple probably makes something too. Motor oil does not have any extreme pressure additives, however using it (or even ATF) in geared transmissions has been popular for about the last 15 years. There doesn't seem to be any issues with using it, but that's a little hard to quantify. There's been a lot of threads on it over the years, but not really a lot of failures that you could point at being from the oil used. If your synchos are shot after 500000 miles, you probably shouldn't blame the oil. :rotfl2: Link to comment Share on other sites More sharing options...
DirtyComanche Posted July 1, 2017 Share Posted July 1, 2017 Is there any way to tell physically which transmission one has? Or is it safe to assume my '90 4.0 manual is AX-15? The Peugeot case is split down the length of the trasmission, with a split line roughly on the very bottom and the very top. The AX-15 is a split by a band that goes around the entire case, near the shift tower. The Peugeot also uses some weird square metric internal plugs. Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted July 1, 2017 Share Posted July 1, 2017 The Aisin manual transmissions are easy to tell by the middle bracket holding the two halves of the case together. Here is a picture somebody else posted on the differences between Peugeot and AX15 Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
crumbscomanche Posted July 2, 2017 Author Share Posted July 2, 2017 There's probably as many opinions on fluid to use as there is members of this forum. You're supposed to use an API GL-4 oil according to the OEM, but that is an obsolete standard. Chrysler later decided that 10w30 motor oil (IIRC) was acceptable. I used Lucas 75w140 Synthetic last time. It is a API GL-5 oil, and is listed to exceed the requirements of a API GL-4 oil. But it might eat the synchos, although technically it shouldn't as if it exceeds the GL-4 spec. Personally I doubt it will and feel that was something of an overblown issue to begin with, probably exaggerated by the formulation of the early GL-5 oils that were quite likely to corrode yellow metals. There's lots of AX-15s running around with the cheapest 80w90 that the quick lube pumped into them, and failures are rare. A better oil might have been the Redline MT-90 75w90. I can't buy it easily, so I wouldn't. Amsoil MTG would probably be the best option, but it's quite pricey. Royal Purple probably makes something too. Motor oil does not have any extreme pressure additives, however using it (or even ATF) in geared transmissions has been popular for about the last 15 years. There doesn't seem to be any issues with using it, but that's a little hard to quantify. There's been a lot of threads on it over the years, but not really a lot of failures that you could point at being from the oil used. If your synchos are shot after 500000 miles, you probably shouldn't blame the oil. :rotfl2: Thanks for the feedback. I run the Mobil1 10w30 High Mileage full synthetic in my engine, would that be acceptable then for the tranny AND t-case? Or do you think it'd be more advisable to use the the 75w140 I'm putting in the diffs? Also mobil1. Link to comment Share on other sites More sharing options...
Jeep Driver Posted July 2, 2017 Share Posted July 2, 2017 TC gets ATF. I have about 40K on 40W and Lucas in both difs and 30W in the AX5. I'm the poster child for combating conventional wizdumb. Link to comment Share on other sites More sharing options...
omega_rugal Posted July 2, 2017 Share Posted July 2, 2017 Is there any way to tell physically which transmission one has? Or is it safe to assume my '90 4.0 manual is AX-15? from the top remove the shifter boot and see how many bolts hold the shifter assembly, 3 for a BA10/5 and 4 for the ax15 Link to comment Share on other sites More sharing options...
crumbscomanche Posted July 2, 2017 Author Share Posted July 2, 2017 TC gets ATF. I have about 40K on 40W and Lucas in both difs and 30W in the AX5. I'm the poster child for combating conventional wizdumb. Cool, thank you. So to recap, I will use Mobil1 10w30 High Mileage in the AX15 (4 qts, right?), and 75w140 in the diffs. For the t-case, does it matter if it's ATF or ATF-4 in a 1991? I will probably go with Castrol or Royal Purple depending what they have in stock at AZ tomorrow. Unless anyone has something else they'd suggest I look into! Also, do the Comanches have the NP231? I appreciate all of the help, this community is extremely helpful . :MJ 1: . Link to comment Share on other sites More sharing options...
MeanLemons Posted July 2, 2017 Share Posted July 2, 2017 The NP231 is forgiving when it come to the choice of ATF to use in it. ATF4 is fine If you live in colder climate, Redline MTL would be excellent choice. Otherwise MT-90 would be fine. Conventional oil is fine. I have no experience with that bit read it to be a good choice. Link to comment Share on other sites More sharing options...
crumbscomanche Posted July 2, 2017 Author Share Posted July 2, 2017 The NP231 is forgiving when it come to the choice of ATF to use in it. ATF4 is fine If you live in colder climate, Redline MTL would be excellent choice. Otherwise MT-90 would be fine. Conventional oil is fine. I have no experience with that bit read it to be a good choice. I'm in socal so I am more concerned about heat. It pushes 100F pretty much everyday now June-Sept. And most of the local OHV parks are at higher elevations, which is why I steered toward the synthetic. Link to comment Share on other sites More sharing options...
DirtyComanche Posted July 2, 2017 Share Posted July 2, 2017 For the record, you can put 10w30 in the tcase. NP/NV is not on board with it, but it's not likely to cause any issues. Anything thicker (gear oil) doesn't pump well and will cause issues. I don't think I'd do this, but maybe a 0w synthetic I'd consider... I don't feel there is much point in trying something like this either way though. The type of ATF you use in it does not really matter, +4 is only called for because the tcase is in a Chrysler application. They called for Dex/Merc prior to Chrysler. GM called for +3 in their NP231s. All the tcases are functionally the same. I wouldn't put straight 40w in a diff. :dunno: I use the same 75w140 synthetic in my axles as in my tranny. These choices are based on the assumption that I'm going to subject the components to massive abuse. Link to comment Share on other sites More sharing options...
crumbscomanche Posted July 4, 2017 Author Share Posted July 4, 2017 thanks for all the help everyone - successfully changed out the diff and tranny fluids, and everything looked great. I am having some trouble with the 30mm t-case drain/fill bolts, but I soaked them with pb blaster today and that will hopefully make it an easy job tomorrow. The mobil1 high mileage 10w30 made a noticeable difference with shifting. Sounds and feels great! Link to comment Share on other sites More sharing options...
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