The rear axle pinion seal may leak causing fluid loss and possible internal rear end damage. Replacing the faulty seal will commonly correct this concern.
Car Problem Reports
Cadillac CTS-V Rear Axle Pinion Seal May Leak
Cadillac CTS-V Problem
Average Mileage: 104,376 mi (95,753 mi - 113,000 mi)
Visitor, 2005 Cadillac CTS-V, 95,753 mi
Rear Pinion seal has been leaking, slow leak and progressively became a serious leak. Find it asinine that GM/Cadillac decided to put the standard CTS Rear Differential in their performance model CTS. Even worse...regardless of how meticulous you are about maintaining the fluids (proper or early service interval) all (even the latest or last gen) of the differentials in the CTS V's will eventually whine due to GM using a poor designed differential that shouldn't have even been used for the base model CTS.
Visitor, 2004 Cadillac CTS-V, 113,000 mi
My CTS-V has had 3 rear ends replaced. One before I bought it (previous owner) and 2 since 60K miles.