BMW Repair: 1999 BMW 540i Lifter noise, synthetic oil change, castrol syntec

Question
I just purchased this vehicle from the original owner. At the time of purchase there was absolutely no unusual engine noise and it was always serviced at his local BMW dealership.
After driving the car home and around for the first week I had the oil changed by my local mechanic. I had the entire car inspected and a fresh Mobil 1 5w-30 full synthetic oil change along with filter. Since that time I have had a lifter knock that seems to be getting worse. I took the car to the BMW dealership and had several mechanics listen to it. Although they didn't have any concerns of engine failure, all they could suggest is to use Castrol Syntec on the next oil change and until that time try some Wynns engine oil treatment in it.
Does this sound like good advice to you. I understand the self adjusting hydraulic lifters cannot be adjusted either.
This is a 48,000 mile vehicle.  Vin #WBADN633XXGM63225


Answer
the previos owner may have added some additive to quite the problem. does the car have the sticker telling use syn oil and if not use 15w40 "organic" oil. the valves can not be adjusted. the noise could also be the vanos unit if the noise is more in the front of the engine
I don't know what else I could have told you Paul. The oil treatment I've never heard of and for engine lifter noise the oil type is really the only thing that fixes lifter noise other than replacing all the lifters, which is expensive. I've never had an m62 with bad lifters so the oil should be addressed first. I have replaced vanos units for the noise. Good luck and maybe I can help you with another problem in the future.
                    Kimber