This is the engine that made the VW-Audi oil sludge affair famous. The oil capacity is tight to begin with (just 3.5 litres in the longitudinal engine B5 Passat and A4), the turbo returns hot oil, and the extended "longlife" service interval cannot take it: the oil thickens, congeals into sludge, and blocks the screen of the oil pump. The symptoms are low oil pressure, the warning light, slow draining oil, greasy deposits at the filler neck and on the filter, and finally limp mode. VW acknowledged the fault in 2004, gave an extended warranty, and even reimbursed repairs already paid for. The clean-up is a substantial workshop bill; and if the pump has already stopped delivering, the engine pays for it.