Originally Posted by BMRLVR
I can't say for sure what the ticking is in your engine, but, I can tell you I have some intermittent ticking that sounds just like that in my car but it only occurs right after an oil change, and then it goes away completely after a few days. Since it is an intermittent tick, I have concluded it is valve train noise in my car. Since hydraulic lifters don't like heavy oil, I think that the 10W60 needs a chance to shear down a bit (as it has been known to do) and then the lifters are happy with the viscosity. One thing I am sure of, is if the noise comes and goes it most likely isn't a bearing noise. The S65 has a noisy valve train, and hydraulic lifter noise can come and go at varying volumes and frequencies. Bearing noises almost always start off subdued and get louder and louder as the issue progresses, until finally there is a failure or excessive loss of oil pressure, enough to turn on the oil pressure warning at idle usually. One thing to note about bearing noises, is that they have a specific frequency and it is directly related to engine RPM, they are almost never an intermittent noise.
Take the car out and drive the piss out of it, Lots of high RPM/redline driving. This will do two things, 1)It will ensure the lifters are full and all air is blead out of them and 2)The oil is at full operating temperature. One other thing of note is that the check balls in hydraulic lifters sometimes won't seat properly seat if there is debris in the oil. ensure you are changing the oil at 7500 mile intervals max, BMW's recommended oil change intervals are just plain too long.
Keep me up to date on how you make out, I am very interested to see if your engine stops making this noise!
Awesome, thanks for the feedback. The issue seems to manifest itself after I give the car a good beating. It never happens when the car is cold - seems only when the oil gets heated up and thins out.