Hey guys, considering transmission fluid is a fiercely debated topic in the M939 and M35A3 trucks I figured I’d go ahead and start a thread concerning it for us.
All MTVR variants current as of this posting utilize the Allison HD 4070P , a robust 7 speed automatic. Here is a list of Allison Approved fluids you can use in your truck.
Please note where it says “off-highway fluids” and keep in mind that if your truck is going to be used at any point off-road, at speeds below 30 mph for more than 5-10 minutes anytime during the life of the truck you fit the qualification for using these fluids. The military has had excellent success with these transmissions running motor oil.
I do not recommend converting these transmissions to ATF for any reason, you will never get all of the old motor oil out and the cost to rebuild one of these is significant if you cause any damage in the process. The motor oil in this approved list will protect your transmission on and off-road with the small catch that if you’ll warm up your truck for 10 minutes before departure at the start of the day you shouldn’t experience any accelerated wear from being a higher viscosity lubricant.
In summary, one of the best things you could potentially do for your truck after initial inspection and subsequent recovery is to change all fluids, including the transmission oil. Oh and don’t forget the filters![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
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All MTVR variants current as of this posting utilize the Allison HD 4070P , a robust 7 speed automatic. Here is a list of Allison Approved fluids you can use in your truck.
Please note where it says “off-highway fluids” and keep in mind that if your truck is going to be used at any point off-road, at speeds below 30 mph for more than 5-10 minutes anytime during the life of the truck you fit the qualification for using these fluids. The military has had excellent success with these transmissions running motor oil.
I do not recommend converting these transmissions to ATF for any reason, you will never get all of the old motor oil out and the cost to rebuild one of these is significant if you cause any damage in the process. The motor oil in this approved list will protect your transmission on and off-road with the small catch that if you’ll warm up your truck for 10 minutes before departure at the start of the day you shouldn’t experience any accelerated wear from being a higher viscosity lubricant.
In summary, one of the best things you could potentially do for your truck after initial inspection and subsequent recovery is to change all fluids, including the transmission oil. Oh and don’t forget the filters
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