Here you go-- Google is your friend!
Very detailed explanation and procedure.
Anyways best things to do is, take the car for a 15-20min highway driving keeping the Engine RPM above 3000(I ran 4th gear Manual mode on highway so that oil pump builds enough pressure).
Ticking Noise SBSI B 11 09 07 -N52 Engine HVA System
This Service Information bulletin supersedes SI 11 09 07 dated April 2008.
designates changes to this revision
Intermittent Hydraulic Valve Adjuster (HVA): “Ticking” or “Rattling” Noises
All E82, E83, E85, E86, E88, E60, E61, E70, E90, E91, E92, and E93 with the N51, N52 or N52K engines
An occasional ticking or rattling noise from the HVA elements may occur during cold engine starts or frequent short-distance driving.
In these situations, the HVA elements may not yet have been supplied with sufficient amounts of air-free oil. This condition will not cause any damage to the engine, and usually remedies itself with a longer driving distance or operating times at full operating temperature.
In the event of a customer complaint, please perform the following the HVA bleeding procedure.
The bleed time may take anywhere from between two minutes and (in rare cases) to a maximum of 30 minutes. This procedure is to be performed on a level surface with the vehicle stationary, and in a properly ventilated area.
Engine oil level correct – neither underfilled nor overfilled
Engine running at operating temperature
Bring the engine up to an operating speed (no load) of 2000-3000 rpm and maintain this condition for three minutes (bleeding procedure).
Let the engine idle for 15-30 seconds and reevaluate whether the noise is still present or not.
Engine quiet – procedure is finished.
Engine noise is still present – repeat the procedure; perform steps #1 and #2 up to a maximum of 5 times.
Only if the noise remains after performing the bleeding procedure 5 times: proceed by performing the procedure for a final time, also at an engine operating speed of 2000-3000 rpm, but for a total time duration of 15 minutes.