Hey all, I am planning to change all my fluids next Saturday, and need some help with the fluids to use...1997 F-150 4x4 offroad 4.6

Rear/front diff- I know it needs 75w90. Im not sure if I have limited slip or posi rear...(use the limited slip additive?) Should I go ahead and take the diff covers off and make sure there is no sludge...I have no clue when it was changed last...

Transfer case- Needs ATF. Is it a good idea to go ahead and change this fluid too?

Tranny-Need to put a new rear seal on it (push in type at driveshaft) So, I figure I would go ahead and change the fluid and filter. Its still red, but Im not sure what kind of fluid is in there, and Im sure it will leak out when I take the driveshaft out.

I guess Im just wondering what brands work best...please help!

Thank you all in advance!

 

Im a fan of Amsoil...

 

Ford now specifies synthetic 75w-140 for the rear end. Most contain a friction modifier so there is no need to add more. The front end still calls for 75w-90, synthetic or not the choice is yours. Be sure to use a Mercon V rated transmission fluid in your tranny, Ford went to this fluid years ago to cut down on shudder problems. Many multi-vehicle or universal labeled fluids are Mercon V, they'll work fine. The transfer case calls for regular Mercon which is being fazed out. If you want to use the same fluid you put in your transmission in your transfer case that would be fine or you could save a few bucks and just buy some inexpensive Mercon.

As far as brands go you'll find fans of Amsoil, Mobil 1, Royal Purple, whatever's on sale--you get the picture. Decide what you're willing to spend and go from there.

 

Use Royal Purple all around!!!

 

Valvoline ATF Merc V gets my vote. Worked great in my old 98.

 

Plain ole Mercon V ATF fer yer transfer case and the 4R70w is my 3cents.

Adrianspeeder

 

HI!... I run REDLINE D4 in the tranny/power steering, ROYAL PURPLE in the diff, and MOBIL 1 in the engine.