There is a knocking type noise for 2 -3 sec on cold or warm startup. Audi regional tech supposedly listened to the car and "didn't hear it". My guess is the porter started the car outside, drove it in and once it's started, the noise doesn't repeat unitl it's idle for an hour or more. Is this common issue? Could a high mileage Castrol Syntec solve this issue? There's 51K on the engine. Still under Audi Cert used car warranty. By the way, can you tell where the access to the oil filter element housing is located on this model/yr? Thanks!

 

chances are there is crap oil in the car to start with ( 51k ) isnt high its nearly new, put some 05W/30 or mobil 1 0W30-40because the oil needs to me thin on these engines to get round quick

 

I had the same problem in my 2004 A8 !
I have tried everthing but after that the dealer found the problem & it was from my Cylinder Heads so it was changed and now the problem is solved.

So in ur side try to flush the oil 2 to 3 times & if the sound was still there, then definetly its from the Heads ..

 

well all what i know is that my 2006 audi a8l has similar problems like when i start it and turn it off it makes a rumbaling noise to it and that i just got a new oil change by taking it to my local audi dealer i told them the same exact story but they said nothing
I think that maybe when i put the air conditioner on in the car before it gets hot then thats the problem