My wife's S3 was 11 months 29 days old when at 7900 miles I sent it to an Audi main dealer for oil service on 30 Dec 2010. After 40 miles I discovered oil underneath it. There was no reading on the dipstick and the underside was coated with oil. There was visible oil contamination on the paintwork. I had it recovered to the servicing dealer and viewed the inspection which revealed under 2 litres of oil [from 4.8L makers capacity] remaining in the engine. The defect was identified as a known fault in which the drain valve in the oil filter housing sticks partially open and allows high pressure leakage past a dust cap. The main dealer has been entirely helpful and responsive so far, including use of a courtesy car. Their suggested course of action is to replace the filter housing, change the oil and filter, lift the cam-cover to allow inspection of the wearing surfaces [scuffing and overheating]and decontaminate the underside, brakes and paintwork. Also to do an external oil pressure indication when reassembled to check within makers specification. The possibility of engine /turbo damage is to be dealt with by attaching a record of this problem to the service/warranty so that if there is a failure in the first 100k it will be met [presumably] by Audi. I am told that with less than 2l of oil and a warning light triggered at about 1 bar[15psi] {which had not come on} I should not worry about mechanical damage. I am mindful that oil cools and lubricates and modern turbo engines rely on a proper supply. I am getting the drained oil tested for contamination/overheating, it is very dark for 40 miles running. I am concerned for the following reasons; 1. My wife's 1 year old car, on which she relies, may itself be damaged and unreliable in either the short or longer term. 2. Possible resale problems. 3. Warranty/Repair problems, particularly if the dealer is no longer in business. I wish to be back in the position I was in before this problem occurred. I am puzzled that Audi appear to have a problem with this vital component which is known to servicing dealers.