ATF for freshly rebuilt M5OD

Joined
Jun 12, 2020
Messages
591
Location
SW Missouri
Looking for some advice here, I jest spent over $2300 to have the M5OD rebuilt in my 2003 Ranger. The shop has requested that I stay with a Dexron III/Mercon fluid. I would typically have installed some form of MTF like Synchromesh and have even used Low-Viscosity Hygard from John Deere in this transmission in the past. The issues requiring a rebuild were not related to a lubrication issue per the shop other than likely a lack of maintenance and abuse from the fleet that owned the truck for the first 200k miles of it's life. The shop uses a Citgo ATF that they buy in bulk "because it's cheap and works" per the owner.

Do any of the available ATFs stand out above the rest in this application? I keep Schaeffer 204 here and have access to Walmart, Oreilly's, anything on the internet, and our local farm Co-op (MFA). I just got home from a 1100 mile road trip and want to change it soon.
 
Joined
Feb 6, 2021
Messages
774
Valvoline maxlife has calcium in it I believe, while castrol transmax doesn't.
transmax uses magnesium instead
 

Creekside

Thread starter
Joined
Jun 12, 2020
Messages
591
Location
SW Missouri
Valvoline maxlife has calcium in it I believe, while castrol transmax doesn't.
transmax uses magnesium instead
I know that calcium is used as a detergent in engine oil but is it used the same way in ATF too? Is that what the magnesium is used for too? Wondering how much that matters in something like a manual transmission.
 
Joined
Oct 6, 2020
Messages
1,017
if the shop wants you to stay with dex 3, it’s license has expired, so you could go with a dex/merc (not the low viscosity)
 
Last edited:
Joined
Feb 6, 2021
Messages
774
I know that calcium is used as a detergent in engine oil but is it used the same way in ATF too? Is that what the magnesium is used for too? Wondering how much that matters in something like a manual transmission.
If your using a manual transmission then use something on the thicker side of ATF, so what mrlawnguy said , dex/merc.

It shouldn't matter too much in your manual transmission either, but the optimum viscosity is very important.

I wonder why you cant use gear oil
 

JRed

Site Donor 2021
Joined
Jun 1, 2009
Messages
2,592
Location
Virginia
I honestly prefer Pennzoil Synchromesh or GM Synchromesh in any trans that takes ATF. I'm of the opinion that manufacturers that spec ATF in manual transmissions only do so because they already have it on hand and it's one less fluid to stock or keep in inventory, or because they some minute improvement in MPG by using the lowest vis fluid they can.
 
Last edited:
Joined
Feb 6, 2021
Messages
774
I honestly prefer Pennzoil Synchromesh or GM Synchromesh in any trans that takes ATF. I'm of the opinion that manufacturers that spec ATF in manual transmissions only do so because they already have it on hand and it's one less fluid to stock or keep in inventory.
Yep exactly, ATF doesn't do well in manual transmissions, they are outright a gear box that needs high film strength.
 

Creekside

Thread starter
Joined
Jun 12, 2020
Messages
591
Location
SW Missouri
I honestly prefer Pennzoil Synchromesh or GM Synchromesh in any trans that takes ATF. I'm of the opinion that manufacturers that spec ATF in manual transmissions only do so because they already have it on hand and it's one less fluid to stock or keep in inventory, or because they some minute improvement in MPG by using the lowest vis fluid they can.
I believe it started just so Ford could use 3-4 fluids on the assembly line. I'm not a fan of ATF in a manual either and don't think it is the proper fluid for the application at all. The only reason that I'm even considering sticking with ATF for the moment is just in case anything was to happen in the first 5k miles or so.
 

Creekside

Thread starter
Joined
Jun 12, 2020
Messages
591
Location
SW Missouri
You already spent 2300 dollars on it. Spend the 60 and get some redline mtl
I looked into the MTL and it appears to be a lot thicker than their regular D4 ATF, would this be a problem? They also have a high temp atf that is between the MTL and the D4 viscosity. Cost is not really a concern, as you pointed out a cheap fluid in a rebuild that cost this much would be stupid if there's something better.
 
Joined
Apr 1, 2020
Messages
1,644
Location
Pacific Northwest
Not familiar with the M5od, but there are some transmissions like certain T5's that have friction disk synchros which really need the friction modifiers in Dex/Merc to function correctly. Also, some manuals have needle bearings that don't work well with heavy gear oils.

Personally, I would stick with Dex/Merc and change it relatively often.
 
Joined
Apr 30, 2019
Messages
498
Location
kansas
I looked into the MTL and it appears to be a lot thicker than their regular D4 ATF, would this be a problem? They also have a high temp atf that is between the MTL and the D4 viscosity. Cost is not really a concern, as you pointed out a cheap fluid in a rebuild that cost this much would be stupid if there's something better.
they actually have the mt-lv which is just a little thinner than the dex/merc and has their add pack if that viscosity area suits your fancy
 
Top