When car makers get very specific about which trans fluids to use with a particular model trans (MERCON, MERCON V, DEXRON, TYPE F, etc.) and caution you not to mix or use the wrong type.......the question I have is........HOW IS IT THAT SYNTHETIC TRANSMISSION FLUID IS COMPATIBLE WITH ALL TRANSMISSIONS? Please clarify if I my statement is wrong. I am sure thats what I read. I used MOBIL 1 SYN TRANS FLUID in a Honda Accord with no problems, but that is my only experience. THANKS.

 

I am no expert on tranny fluids but I recall, that most of them will have fine print saying meets such and such spec for yadda yadda type fluid.

Dexron and Mercon are close enough that I have seen dual capability fluids for decades. F is different enough that it is not compatible with Dexron/Mercon so I have read. Mercon V is supposedly slightly different from Mercon so that you are not downwards compatible but supposedly Ok to move up to V.

I am guessing the syns consider their product to be upwards compatible from the Dexron/Mercon types. I would think they don't pay a lot of attention to F type since that hasn't been used in modern trannies since maybe the 70s? I could be wrong, but this is my guessing about how they are making their claims.

I have read from a few websites that the syn fluids sometimes don't work as well as the specified fluid. I moved from dino Dexron II to Mobil 1 in a chebby and it seemed to soften my shifts. On other Fords I have heard it makes the shift hard and inconsistent.

Good Luck,

Jim Henderson

 

We need to also take into consideration, the compatability of a fluid, with the tranny's metal, elastomeric materials, like seals, gaskets, & plastic parts & clutch friction material, as well as the fluids "coefficient of friction" properties, when choosing something other than a specified tranny, or power steering fluid.

 

There is no single fluid that cvompatible with all trannies. Dexron/Mercon is probably the most compatible across a big range, but it's definitely incopmpatible with F, for one.

 

Coefficient of friction is the primary difference. GM is the only mfr that seems to have fully backward compatible (to the 1940's!) ATF with the Dexron series. Put it in a Type F tranny and it will slip like crazy. Ask me how I know. DCX now has +4, made by PetroCanada, that is dealer-only, so is the latest Toyota fluid. Since the lockup torque converter came into use, "shudder" has been a problem, and the "answer" seems to be "fine tuning" of the frictional characteristics of the fluid.

Jim