The following engines were reported by the Center for Auto Safety and/or their manufacturers to have a problem with sludge accumulation:
1998-2002 Chrysler 2.7 L LH V6
2001-2002 Dodge Stratus/Chrysler Sebring
1998-2002 Dodge Intrepid/Chrysler Concorde
1998-2003 Saab H engine B205/B235 I4
1998-2003 Saab 9-5 B235 2.3 L
1999 Saab Viggen B235 2.3 L
2000-2002 Saab 9-3 B205 2.0 L
2000-2003 Saab 9-3 convertible B205 2.0 L
1996-2001 Toyota 3.0 L 1MZ V6
August 1996-July 2001 Toyota Camry
June 1998-May 2001 Toyota Camry Solara
July 1997-May 2001 Toyota Sienna
July 1996-May 2001 Toyota Avalon
November 2000-July 2001 Toyota Highlander
August 1998-July 2001 Lexus ES300
January 1998-July 2001 Lexus RX300
1996-2001 Toyota 5SFE I4
August 1996-July 2001 Toyota Camry
June 1998-May 2001 Toyota Camry Solara
August 1996-April 1999 Toyota Celica
1997-2004 Volkswagen VW 1.8t I4
1997-2004 Audi A4 1.8t
1998-2004 Volkswagen Passat 1.8t
http://en.wikipedia.org/wiki/Oil_sludge