WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Crankshaft Seal For Leakage Check
Courtesy of VOLVO CARS OF NORTH AMERICA.
Check the crankshaft seal for leakage.
To replace the crankshaft seal, see the car and model year in question.