Going to change mine as it makes a whistling noise between 30 and 40 mph when it's cold, I don't think it's ever been changed.. What is a good brand and what is the proper viscosity I should use, and yes I searched, but got too many different opinions. Thanks in advance!

 

Just use any syn gear oil 75/80W. The first time I did this job, I used dino gear oil. Then I realized it was just a pain in the azz to do, so I paid a local quick xpress lube shop to do it for me. Used Havoline syn gear oil this time. I won't think about touching it again for at least 60k

 

mobile 1 synthetic 75/90. Pep boys and autozone both have a pump and hose that fits on the quart jug to pump it in the diffy fill bolt. Be sure to get a couple crush washers for drain and fill bolts. Undo fill bolt first. You can even get new drain and fill bolts because if they have not been torqued since 99 you may have an issue getting them a loose right there.

 

Be sure to use a gear oil rated GL5. There are GL4 gear oils, but they are designed for manual transmissions and may not have the EP additives differentials require.

 

Changed mine @ 60k with Mobil 1 Syn, then again @ 70k with Royal Purple. I used the Mobil 1 to really rinse out the old because of what I saw come out. Should be good for another 60k easy!

 

that pump worked like crap!! I bought it and it was a pain to get the suction to work. For all the trouble I went thru It was money well spent to have someone else do it