So I changed my diff fluid this weekend (30k service). As many of you have stated, the rear fluid was shot. Grey in color and smelled bad. My questions is this. The rear diff had a fluid level line that I filled to. The front diff did not. I filled the front until it came out of the fill hole. Is this bad? Will it hurt anything?

 

you typically fill until it starts to flow out of the fill hole unless it has two plugs, then one is drain and the other is fill, same applies as stated above.

Regarding the fluid smell, I guess I have never found any new or used diff fluid to smell good, usually it smells really bad. If you get it in your hair and are single, you may be single for a couple more days

Grey means water, this is not cool.

 

Grey means water, this is not cool.[/QUOTE]

Thats what I was thinking....Mine was black as night.

 

I think with these AAM axles they are to be filled just blow the hole, ¼” to 3/8” give or take. I just filled mine until it was ready to run out.

 

Gray dosen't mean water on these AAM axles. Especially on the first fluid change. They coat the gears with a grayish sealer to keep them from rusting before the fluid is installed. It's normal to see the color like this. Due to the fluid being 75w90 it is a thinner oil and will flow more easily out when doing a change. That's normal also. As far as the smell. Diff oil smells like crap new, used, no matter what brand.

 

I changed my for the second time. It look new and had the oder of my new oil. It felt like the new oil.

 

Spec for filling the diffs is 1/4" below the fill plug +/- 1/4". In other words filling until it comes out the fill plug is fine. The line on the cover is 1/4" below the fill plug.