Ok. I'm gonna switch some of my fluids to synthetic tomorrow, and want to know what are the best brands and weights.

Front & Rear Diff

Transfer case

Power Steering

Also, I saw a post awhile back about flushing the power steering. I would like a link if any of you happen to have it on hand.

 

I would use the same ATF for the transfer case, P/S, and auto trans. The front diff is 75w-90 and the rear is 85w-140. I have used Mobil One synth ATF; and Super Tech Synth gear oil from Wally World in the diffs with good results.

 

PS Flush:
https://www.ford-trucks.com/forums/4...id-change.html

 

I think the rear diff gets 75W-140 syn, Roland...

 

Thanks Roland. If I use syn in the rear diff do I need to add the friction modifier?

 

Joe, I new I saw that somewhere I just couldn't find it again. Thanks.

 

You're right, Joe. I was thinking about the weight we use at work in our OTR trucks.

 

You're supposed to use syn only, and it depends on the fluid. I personally like the type without it and add just enough for it to stop chattering on turns. Too much friction modifier and your limited slip is now limited GRIP...

 

Like Joe said.

 

Does it have to be Motorcraft or will any do the job?

 

Any friction modifier will do...

 

Thank you guys for your help. This will keep me busy for a couple of hours tomorrow.

 

Sorry guys one last question. Do I need to buy new diff cover gaskets or can I use the "gasket in a tube" to get it to seal?

 

Personally i rather get gaskets... Just because if you plan on changing the fluids again you will thank yourself for not using silicon stuff...

 

I looked all over to find a gasket and failed. Just went with the RTV sealant instead of wasting more time and money hunting one down. It was pretty easy to use. (my 1st time) Make sure you circle the bolt holes. No leaks for me!