dnewton3
Staff member
I'll throw in my $.02 here ...
Per the reference page near the top, the Ram trucks have two applications:
Auto T-case
The Mobile LT is a tractor-hydraulic fluid; it's good quality stuff. This is a typical universal tractor fluid that can be used in shared-sump systems that use the fluid for both the transionssion and the hyrdraulics. This is a very common thing in tractors and has been for decades. This is the fluid for the t-case the OP has, and I would say any good quality UTHF will work for this application.
https://www.mobil.com/en/lubricants/for-businesses/heavy-duty-lubricants/products/mobilfluid-lt
Part-time t-case
The part-time t-cases apparently use the Shell Spirax A389 stuff; that "389" reference is a nod to the Allison "TES-389" fluid spec, which is essentially a nod to the old GM Dexron III-h stuff ( they are red-colored ATFs and the Shell product even has "ATF" in it's title). Meaning that this is essentially a lessor cost alternative (read as non-synthetic) option as a traditional automotive ATF. The Allison TES-295 is their high-end synthetic ATF spec, and the TES-389 is their common-man non-syn ATF spec. In these applicaitons (which does not include the OPs truck), just about any decent Dex/Merc fluid will suffice. A cautionary note is that GM and Ford don't license those old fluid specs and haven't for a while, and so if you use a "Dex/Merc" variant, you'll want to assure yourself it's a good product from a reputable company. For example, Mobil's "D/M' is actually an approved and licensed Allison fluid, even though "Dexron III-h" and "Mercon" are not licensed by GM and Ford. But Allision keeps the spec alive for a non-syn choice in their fluid spec line-up. Reputable companies like Mobil, Shell, Castrol, Valvoline, etc are going to make their Dex/Merc fluids to a good quality level despite a lack of the GM and Ford licenses being issued.
https://allisontransmission.com/parts-service/approved-fluids/on-highway-fluids
I am not convinced that the Amsoil look-up tool is spec'ing the right fluid for the OPs application, I think they are being generic and not realizing that there are two fluids in play here. Amsoil's site shows the same two ATF products for all three t-case applications. To me, that does not seem correct; they are ignoring the UTHF stuff. Maybe it's their opinion that the ATFs will suffice for the UTHF application? I do see that Amsoil has an agricultural section, and in there they have a "hydrostatic" trans fluid, but it's not really marketed as a UTHF; it's more of a hydrostat fluid like is used in zero-turn mowers, but it is in their "agricultural" section ... for what that's worth. Might be worth a try to reach out to Pablo for his opinon here.
I would use any decent quality UTHF. I would recommend getting a synthetic one and not having to change it as often.
Per the reference page near the top, the Ram trucks have two applications:
Auto T-case
The Mobile LT is a tractor-hydraulic fluid; it's good quality stuff. This is a typical universal tractor fluid that can be used in shared-sump systems that use the fluid for both the transionssion and the hyrdraulics. This is a very common thing in tractors and has been for decades. This is the fluid for the t-case the OP has, and I would say any good quality UTHF will work for this application.
https://www.mobil.com/en/lubricants/for-businesses/heavy-duty-lubricants/products/mobilfluid-lt
Part-time t-case
The part-time t-cases apparently use the Shell Spirax A389 stuff; that "389" reference is a nod to the Allison "TES-389" fluid spec, which is essentially a nod to the old GM Dexron III-h stuff ( they are red-colored ATFs and the Shell product even has "ATF" in it's title). Meaning that this is essentially a lessor cost alternative (read as non-synthetic) option as a traditional automotive ATF. The Allison TES-295 is their high-end synthetic ATF spec, and the TES-389 is their common-man non-syn ATF spec. In these applicaitons (which does not include the OPs truck), just about any decent Dex/Merc fluid will suffice. A cautionary note is that GM and Ford don't license those old fluid specs and haven't for a while, and so if you use a "Dex/Merc" variant, you'll want to assure yourself it's a good product from a reputable company. For example, Mobil's "D/M' is actually an approved and licensed Allison fluid, even though "Dexron III-h" and "Mercon" are not licensed by GM and Ford. But Allision keeps the spec alive for a non-syn choice in their fluid spec line-up. Reputable companies like Mobil, Shell, Castrol, Valvoline, etc are going to make their Dex/Merc fluids to a good quality level despite a lack of the GM and Ford licenses being issued.
https://allisontransmission.com/parts-service/approved-fluids/on-highway-fluids
I am not convinced that the Amsoil look-up tool is spec'ing the right fluid for the OPs application, I think they are being generic and not realizing that there are two fluids in play here. Amsoil's site shows the same two ATF products for all three t-case applications. To me, that does not seem correct; they are ignoring the UTHF stuff. Maybe it's their opinion that the ATFs will suffice for the UTHF application? I do see that Amsoil has an agricultural section, and in there they have a "hydrostatic" trans fluid, but it's not really marketed as a UTHF; it's more of a hydrostat fluid like is used in zero-turn mowers, but it is in their "agricultural" section ... for what that's worth. Might be worth a try to reach out to Pablo for his opinon here.
I would use any decent quality UTHF. I would recommend getting a synthetic one and not having to change it as often.
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And it still uses Mopar Transfer Case Fluid.
-As they've been plagued with AFM issues lately and there is even a class-action lawsuit that was filed this month. I know, I know, a class-action lawsuit will not help the customers as much as it will make money for the lawyers. Still, I wouldn't touch a recently built GMC/Chevy truck with a ten-foot pole, lol.
