The lawsuit, which includes 1997-2004 Audi A4s and 1998-2004 Volkswagen Passats, was filed in St. Clair County Circuit Court on March 22, 2006. Lead plaintiff in the suit is Mildred Kasten, who owns a 1998 Passat.

According to the lawsuit:

On August 2, 2004, owners of the affected vehicles were informed by letter that they would need to use more expensive synthetic oil, over less expensive petroleum-based oil. Vehicle warranties are honored only for owners who can prove they have maintained their vehicles on schedule.

In a bulletin issued to Volkswagen technicians on August 5, 2004, the the use of a larger oil filter -- which requires the use of more oil -- was prescribed. Volkswagen did not notify owners of the vehicles and members of the class that, in addition to requiring more expensive synthetic oils, technicians must use a larger oil filter and more oil when changing the engine.

The complaint states "...The cost of required oil changes of the affected vehicles more than doubled from an average cost of $30 per oil change to $65 per oil change." The complaint also alleges that even if owners had complied with the new requirements specified in the August 2004 letter, they could experience engine failure due to the use of the previously required oil filter.

"A class action will ensure an orderly and expeditious adminstration of the claims of the class, in that such administration will foster economies of time, effort and expense, as well as uniformity of decision." states the attorneys that filed the case.

The suit claims Volkswagen breached its contract with owners by unilaterlly changing warranty terms resulting in costs that doubled, violated the Illinois Consumer Fraud Act and became unjustly enriched.

The lawsuit seeks to recover the money the vehicle owners spent on synthetic oil changes.