Need to do Tranny and differential fluid on my Expedition. Bought it 10k ago check the Fluid in the tranny and is not smelling burned, but it has a brown hint to it; however no shreds of metal found with in the fluid itself. So I need to find out what is the best tranny fluid for my truck and what is the best gear oil for the differential I looked at the tag and is says to use synthetic fluid but not sure how thick should it be

 

For the tranny you should only use Mercon V, there are a few makers of it (Mobil, Advanced) but I would stay with Motorcraft. As for diff fluid, I believe its 75W90 and the Motorcraft is a synthetic fluid, Royal Purple makes a synthetic diff fluid as well. Your owners manual will specify the weight but I'm nearly positive its 75W90.

 

Tranny= MerconV I just did mine last week, I bough a case of 12 + 3 more thinking that I was gonna use them all, but my truck was not equipped with the TC plug to drain it (Torque Converter) so I just ended up using 5 of them. Used Motorcraft Mercon V @ $3.10.
Also changed the differential fluid about 2 . 3 weeks ago, it required 75-140 and 4 oz of friction modifier. 2 quarts of fluid were about $35 for both in autozone, (Mobil1) which is syntethic and paid around $5 for the friction modifier at the stealership.
My truck is 4x4 and the rear differential calls for 75.140 whereas the front one requires 75-90 according to the manual. Also I changed the tranny filter, but I was reading through the manual and it says that it does not require the filter change until 150,000 miles, I also found a little plastic strange little thingy inside my tranny, I was scared for a minute, I thought it was falling in pieces, Called my mechanic and told me that it was normal, since it was the first tranny fluid change, and that little piece was put there to keep impurities to get into the tranny. Good thing was that the tranny was not falling in pieces, the bad one, was that at 45k it was her first tranny fluid change

2003 Ford XP Eb 4x4.
5.4 Engine.
4R70W Tranny.


happy valentine.

Gerardo

 

Before using Mercon V, read your manual or look at your dipstick to confirm that's what you need. My Expy uses Mercon fluid.

 

4r100 tranny uses Mercon
4r70w tranny used MerconV

 

Should I also add that Lucas additive to the transmition, this is the frist car that I have owned that the tranny is not slipping so I kinda wanna take care of it, you know!