Following in the footsteps of Toyota, VW and Audi, Saab has extended the warranties for the 2.3-liter (1998-2003) and the 2.0-liter (2000-03) engines for the possibility of sludge buildup. The sludge buildup can lead to engine failure. The warranty stretches the coverage to eight years from four. As of right now, the mileage limitation has not been determined. Chrysler is a holdout in the sludge wars, stating that the sludge that has appeared in hundreds of their 2.7-liter V-6s is the result of infrequent oil changes, not an inherent design flaw. Interesting argument.