1996 XJ 353,000 miles

Going to replace fill plug in 8.25 rear end and top off the gear oil (Mobil1 75W90). Picked up some AutoPro UV oil dye at AutoZone, but the package does not specify differential/axle oil. It does say it is intended for engine, fuel, and ATF. Elsewhere on the internet saw a blurb that it was safe for all petroleum products.

Any issues I am not realizing here?

BTW, the Harbor Freight small orange funnel set ($1 and change) seems like the **** fer dolly on getting the few ounces of dye from the bottle into the diff. I do have one of their small fluid pumps for adding the oil too.

Also plan on replacing the axle breather line, but no clue how to check if breather fitting is clear and how to clean that if it is obstructed.

 

Just guessing here but thinking you can just blow into the line while attached to the brake hose.
With the diff plug off.
Then blow into the line while attached to the uni-body and see if it flows free.
I always assumed there is some sort of check valve on the inside of the uni-body,
to keep water from getting in there but like I mentioned before never have been able to confirm this.
Thinking somthing like the transfer case has. Look closely at the end of the hose in the upper left.

 

I am working on the rear end, Chrysler 8.25. Not up to that stuff in the middle of the driveline yet.

 

What?
The transfer case shot was just to show you the check valve I believe to be in the uni-body for the rear diff.

 

What's the point of adding dye to the diffs? They only leak from a few places, and its usually pretty obvious where the leak is coming from.

 

Just to know early as possible.