Rear Diff Questions
#1
Skint
Thread Starter
Rear Diff Questions
First off i know there are probably 100k plus different answers to what I am about to ask but I will ask anyways. I am changing my rear diff cover and oil this weekend on my 04 FX4 3.73LS, and my manual says use 75W-90 gear oil, ok great! EVERYTHING i read on these forums says everyone is using 75W-140 with no mention at all about 75W-90. I have always heard go by the manual on this sort of stuff. I am going to use Mobil1 Full Synthetic LS and add a tube of the Trans-X mod. no matter what. So i was just wondering if anyone has any input on this
#3
Senior Member
Isn't 75/90 what you use for the FRONT diff on a 4x4? In my rear diff I put 75/140 (2x4)...used Amsoil severe gear. Remember to soak out the sump in the bottom of the differential. Just saying.
#4
Junior Member
Join Date: Apr 2013
Location: Central Wisconsin
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
My manual says 75W-140, and that's what the mechanic put in Tuesday when he replaced the rear pinion seal. Mine has the 3.55LS fwiw, but it'd probably be worth it to look at the newest version of the manual if Ford's got it.
#6
First off i know there are probably 100k plus different answers to what I am about to ask but I will ask anyways. I am changing my rear diff cover and oil this weekend on my 04 FX4 3.73LS, and my manual says use 75W-90 gear oil, ok great! EVERYTHING i read on these forums says everyone is using 75W-140 with no mention at all about 75W-90. I have always heard go by the manual on this sort of stuff. I am going to use Mobil1 Full Synthetic LS and add a tube of the Trans-X mod. no matter what. So i was just wondering if anyone has any input on this
#7
Skint
Thread Starter
I didnt add any FM with the RP, but I have not had any chatter, shudder, etc since Saturday. I may add some later if i hear anything-Thanks
Trending Topics
#9
Skint
Thread Starter
#10
Senior Member
I only used a single bottle of the friction modifier in my diff, and it calmed it down a great deal - but I still get chatter occasionally - I think I am going to slip under there, pop the plug and squirt as much of the second bottle in as I can and replace the plug real fast...