hello i recently worked on a 07 nissan titan for a friend of mine i changed the rear differential and mistakenly put 75w-90 synthetic in. he took a trip to canada and when he got back he stopped in to check it over it appears that the axle seals as well as the pinion seal is now leaking i took the 75w-90 out and put 75w-140 in but he says it still is leaking some has anyone ran into a problem like this please help!!

Since the thin side is 75 W that shouldn't have made a difference.

Sure you didn't over fill it or better yet are you sure they weren't leaking before the change. A lot of us have had leaking axle seals.

On a happy note this is a great time for your friend to throw a tru trac in his truck.