When you are looking for the object that is known as synthetic gear lube you can go to a store that is known as Wal-mart and buy gear lube for the car that you are driving.
Synthetic lube
The best way to find out what gears to lube on a Ford Freestar is to start by looking in your manual. The manual has alot of important information. If it isn't there, visit the dealership.
75W-90 synthetic gear oil
answered on dootalk. 75W90 synthetic gear lube
I can find no recommended oil for this application. If it were mine I would run AMSOIL Severe Gear® Synthetic Extreme Pressure (EP) Gear Lube 75W-90
You can use synthetic 75W-90 if you are using a gasket between the diff cover and the housing. If you are using RTV sealant with no gasket, use the conventional gear oil 80W-90. It seems the synthetic lube dissolves the RTV sealer.
Your Lubricant is too cold to flow & lubricate efficiently. Switch to a Synthetic Lube. Suggest AMSOIL Gear Lube or AMSOIL Synthetic Manual Transmission Lubricant. See your Owners Manual for correct viscosity.
maybe
Differential, Front .....GL-5[4][5]80W-90SAE 80W-90 Synthetic Gear LubeSevere Gear 75W-90SAE 75W-90 Synthetic Gear LubeDifferential, Rear .....GL-5[6][7]80W-90SAE 80W-90 Synthetic Gear LubeSevere Gear 75W-90SAE 75W-90 Synthetic Gear LubeTransfer Case,W/ Other TRC.....AF3Synthetic Automatic Transmission FluidTorque-Drive
That will depend on which Tranny you have there were 2 see links below.Manual Transmission,NV3500.....GLS [2]Manual Transmission,NV4500.....GLS [3]2. GLS is a special gear lube, GM part no. 12345349.3. Synthetic gear oil, GM part no. 12346190 or equivalent.For the NV3500 RecommendAMSOIL Synthetic Synchromesh Transmission FluidFor the NV4500 RecommendAMSOIL Synthetic Manual Transmission and Transaxle Gear Lube 75W-90 Hope This Helps ----
The price for Gear lube varies, depending on the brand and they type of lube you are looking for. On amazon. com you can get a 1.25oz tube of Oster Gear Lube Clipper Grease for under $5.00. You can also get a tube Sier Syntletic Gear Lube Volv0 can run you $185.00.
standard 80/90 if its winter you can use synthetic also still 80/90