15w40 instead of transmission fluid? | Ford Explorer Forums - Serious Explorations

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15w40 instead of transmission fluid?

anthonymtz

Well-Known Member
Joined
November 17, 2014
Messages
221
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City, State
Fort Worth
Year, Model & Trim Level
2004 Ford Explorer XLT
I was just wondering if it would be possible to use 15w40 oil in the 5r55 trans, i know it calls for the mercon v or something similar, I was watching this guy online build a 18' GT 10 speed trans and he filled it with rotella 15w40! So with that being said could it be a possibility for are trans?
 



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Personally, I would like to see an automatic run on motor oil, but realistically it is not designed to do what ATF does. ATF is not only a lubricant, but also a form of hydraulic fluid. It is specially formulated to work with the clutches, seals, and solenoids in an automatic. Motor oil does not have that capability.

TLDR; Don't do it.
 






MUST USE TRANS FLUID SPECIFIED BY FORD FOR YOUR 5R55 TRANSMISSION
Engine oil would kill your trans in short order the 5r auto has very very specific fluid requirements..........do NOT deviate
 






In a manual transmission I have run 10-50W synthetic in lieu of 75-90w. The 10-50w must be synthetic or it will break down too easily. The thinner oil helps the synchros mesh. In a manual transmission the fluid is used to lube in by splash around, and some shear on the gear teeth.

In an auto transmission the fluid is used to transfer force. Our transmission is pretty sensitive to the type. Merc V or nothing.
 












No! Never.
 






Pfft. These guys are by the manual babies. If it works in a 10 speed, it should be even easier on the 5 speed. DO IT.
 






Transmission's reaction to motor oil: :confused2: -> :burnout:-> :splat:-> :dead:

Your reaction: :cool2: -> :burnout:-> :eek: -> :confused2: -> :censored:-> :help:

Our reaction: :nono: -> :rolleyes: -> :popcorn: -> :snicker:
 






Troll?
motor oil would foam up in the torque converter.

No, im no trolling, i really was curious on to why 10w40 was used in a new 10 speed! Its also alot cheaper vs mercon v but looks like im stuck using it haha! Thanks for all opinions, i might try it one day if i run into a spare trans, the guys Instagram that used the oil on his trans build is "Whitem3" he gots the first 10 speed to hit 7's!, Again not trying sound dumb on here but after seeing that i just had to ask my explorer buddies!
 






There can be a big difference in using a fluid in something built for a specific use like racing as compared to a grocery hauler. Drag cars run nitromethane for fuel but using it in a daily driver isn't such a good idea.
 






No, im no trolling, i really was curious on to why 10w40 was used in a new 10 speed! Its also alot cheaper vs mercon v but looks like im stuck using it haha! Thanks for all opinions, i might try it one day if i run into a spare trans, the guys Instagram that used the oil on his trans build is "Whitem3" he gots the first 10 speed to hit 7's!, Again not trying sound dumb on here but after seeing that i just had to ask my explorer buddies!

Cheapest Mercon V is Walmart's SuperTech but I'd still recommend Valvoline or Motorcraft.
 






Stick with Motorcraft Mercon V, IMHO. Transmissions are too expensive to mess around with other fluids . . . .
 






Stick with Motorcraft Mercon V, IMHO. Transmissions are too expensive to mess around with other fluids . . . .
bUt mAyBe iTs bETtEr....
 






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