In my 1988 Ford F150 it has a rear 8.8 axle. I saw the other day after repairing the rear brakes that I have a seal leaking and it's probably the explanation of why I hear a roaring noise over 65 miles per hour. I'm plan on replacing the bearings and maybe getting the whole unit rebuilt but I want to put oil in it in the mean time should I use a thicker oil like 75w 140 to slow its leak down and how do I know if it's a track lock