Hey everybody! I'm new to this forum and have a transmission question. I have a 2002 F-350SD auto and want to switch to using synthetic fluid. What fluid do you recommend? I heard Mobil1 was good.

 

I have a 2002 F-350 4X4 with auto. I use Royal Purple synthetic ATF in the tranny and transfer case. I also use Royal Purple synthetic gear oil in both axels. I used Royal Purple in my drag truck so I now its longevity and its ability to handle abuse.

 

Here's the story as I understand it:
Mercon is specified for your transmission. Mercon V is specified for the new, 2003 and newer transmissions. The seals in your older transmission do not stand up to some of the additives in Mercon V.
Your owners manual says to use Mercon ATF. It emphatically says do not use Mercon V or any fluid which claims to be compatible with Mercon V or any fluid which is compatible with both Mercon and Mercon V. The original Mobil 1 ATF DID meet that requirement. More recently Mobil 1 has been changed, and is now compatible with both, which violates the owners manual. You can still find the old Mobil 1 in parts stores, and by reading the label verify that it is compatible with Mercon and does not mention Mercon v. I imagine that Mobil would say its ok to use in our trucks, but why take a chance?
Ford itself came out with Mercon V for the newer transmissions, and some ford shops a few years ago quit stocking Mercon and claimed that the new fluid would be ok in the older trucks. Then last year Ford put out an ATF that was labeled for both mercon and mercon V. Since it is Ford, I guess it is ok to use, but I don't know if it is synthetic.
Other aftermarket suppliers, like Amsoil, have synthetics which claim to be compatible with both mercon and mercon v. You are then stuck with either believing them or believng your owners manual. I'm sure a properly knowledgeable technical ford guy could tell you whether the aftermarkets are ok or not.
So if you are very conservative, find the old Mobil 1 in a parts store; I did just last winter. If you can't find it, try to find the Ford combination and maybe it is synthetic. If you want to believe ExxonMobil, a very good company, then use the new Mobil 1. You could choose to believe one of the other aftermarkets like Amsoil or Royal Purple if you think their labels are correct.
Warren

 

i run royal purple synchromax atf(specially designed for manual trannys req atf) in the tranny and royal purple synthetic in the case. i like it.

 

Here's how I now understand it. Ford will not be issuing Mercon III licenses any longer, I think in '07. It appears the Mercon V has been reformulated to be compatible with our transmissions. I believe thats probably what the new Mobile 1 formulation is about. Apparently it's fine to run it if all the Mercon III is out. It's not good to mix the two, so a flushing would be in order. Now here's the gray area, I don't know if all the licensees of Mercon V are using the new formulation yet.

I'm sure someone knows more about this than me and I will be corrected if I'm wrong. This is the info I gathered a while back when I was looking for trans fluid. I still had a supply of the old Mobil 1 at last change so I haven't put anything different in yet. I will do some more checking before I do.

 

Royal Purple here got it at COXIMPORTS.com two cases of MAX atf for $181 shipped to my door best price I could find anywhere even though its a ricer store

 

I use AMSOIL. ATF

 

i have some atf fluid that says Dexron III / Mercon and i have a 2000 7.3 - will this be okay - i have some for free so i am hoping for a yes
thanks

 

That's fine. DEXRON III/MERCON is the correct fluid.

 

I am going to with Schaefers 204 SAT for the tranny. I am putting in the valve body from BTS this weekend. Since these guys are the best in the business, I figured I would take their advice and use Schaefers. $125 for 5 gallons. I am also going to be putting Schaefers in the motor, diffential, and transfer case.