M104 Cold start Knock/Tick
 

Hey all,
91' R129 M104-CIS 99K miles.
2 Weeks back changed the oil to MB 299.5 full synthetic with an MB original filter , After using non-brand 5w-30 full syn forever (Stupid me, I should've know to stick with what works..) . Upon cold a Knock/Tick will be present if the car sat for 24 hours. The noise will disappear after 5 seconds ( as the oil pressure gauge will go up to "3"), I changed the oil once again, this time to the Chevron-Delo 400 along with a new MB original filter, Knock is still here.. The car drives well (no other issues). Oil pressure readings:
Cold start idle - 3
warm idle - 2
acceleration - 3.
My driving still is the complete opposite from the italian tune up - which I was told to try..
Any suggestions?

Thanks