I have been chasing an engine oil leak with UV dye and a UV flashlight. While under the car with the light I stumbled on some aqua blue residue on the ZF around the drain plug and one of the bottom cover bolts. The bolt that lit up was wet with oil. It turns that Valvoline gear oil is visible with a UV light. It shows up as a distinctive blue. I was planning to put dye into the ZF sometime later to check for leaks but it is not needed. Only one of the bottom cover bolts is leaking. I will pull it, spray brake cleaner in the hole, and reinstall with Right Stuff around the bolt head and washer. I may need to put Permatex B on the drain plug.
