Same thing just happened to me. My "low oil message" came on yesterday in my 2009 CS with 12k miles. I stopped, put a quart of Mobile-1 and message was gone as soon as I restarted. Now that it's been parked overnight, I'll recheck the oil level.

Update: My oil level was EXACTLY 1-quart low when the "low oil level" message came on.

 

FWIW , these engines seem to consume more oil than other manufacturer engines. not saying its a bad thing , but you have to remeber that on a forced induced engine ring gap tolerances tend to be a bit on the loose side due to all the heat that is generated with boosting it, which inturn leads to a tad more oil consumption .

i made it a habbit of carying an extra quart and stowing it in the rear where the cd changer is for when ever i do get the light .

 

The techs at my dealership said it is completely normal to have to add 1 qt of oil for every 1000 miles I drive in a Cayenne Turbo. I thought this was insane compared to any other car I've owned in the past but after asking multiple people it does indeed seem to be the case...especially with the Turbos. This constant addition and subsequent dilution of crap is one reason why the '05 models (with 9.5 qts of oil in the oil pan) only need oil changes every 20k miles. Other model years have different recommendations for frequency of changing the oil.

As soon as my light comes on I grab a quart of Mobil 1 from the little cubby in the rear side compartment and dump in the whole thing. 1 qt seems just about the right amount. At least thats convenient.

 

I add a quart of oil every 1000 - 1500 miles in my '06 Cayenne Turbo. At first it seemed kinda odd that it needed this much oil since my other turbo car never needed extra oil. I just figure it is part of the way the engine was designed -- besides as others have mentioned, the Cayenne has a nice cubby in the back for holding quarts of Mobil 1.

 

My MB turbo diesel ML320CDI would use about 0.5 liters every 5,000 miles. A liter every 1,000 miles would certainly seem excessive to me; although it is considered to be within spec.

 

The oil light came on in my truck tonight on the way home from work (06 TT S).

What oil should I put in it?

 

Mobile 1 0W40 synthetic.