Help with rear end
Senior Member
Joined: Dec 2006
Posts: 43,542
Likes: 819
From: Joplin MO
Well, Ford themselves specifies SYNTHETIC 75w140 plus XL-3 additive. It's good for about 80k before you have to change it. I have 192k on mine and the LSD still works with no chatter.
The XL-3 stops the chatter. I'd rather have a good quality synthetic in my diff than straight gear oil.
The XL-3 stops the chatter. I'd rather have a good quality synthetic in my diff than straight gear oil.