JaguarXJL15, thicker oil I do not think is the answer as the VVT system needs as thin of oil as possible. The detergent may correct things, it may not. This is where you have to answer the question of : Is the damage due to build up or is it due to wear? If it is build up, then yes, this detergent you are looking at should help. If it is due to wear, that is not going to do a single thing for you.

 

What your engine sounds like still sounds like mine did. I recommend stethoscoping the drivetrain noise.
Otherwise, if you feel the noise is isolated to the passenger bank, pull the supercharger, covers and get a boroscope in there.

 

First I will remove the belts to see if the noise is still there with just the engine running
I will be removing supercharger to upgrade coolant pipes and repair the SC coupler might as well take a look inside the valve train