Hi All, sorry for the delay. The warranty is through Zurich bank and used to be called something else. Either way I got it when I bought the X5 years ago at a MB dealer. The have been great about coverage and the deductable has been an honest $100. I highly recommend them.

With a spin-on filter, which normally should contain an anti-drain-back valve, that would make sense. However, the cartridge filter on this model does not have an anti-drain-back valve, so I don't understand why the filter itself would cause this cold start noise.

I am a fan of OEM filters, as often filters from the same manufacturer have different micron specs for filter media, or slightly different specs that do impact performance. I just don't get it with this particular problem.

Question for you Weasel. Is there not an anti-drain-back valve in the oil filter housing? If so, could it not be tired/worn and a cause of this noise? The valve appears to be part of the housing, and not serviceable by itself, but it fits with the symptom. Just wondering if you have come across this before.

I had that very same thought about there either being a valve in the housing or the o-rings in the housing being hard / worn.

There is a valve in the housing... I haven't taken the valve itself apart just to see the design yet (as I have had the housings off many times for gasket leaks on the I6 motors) But I suspect a simple steel ball bearing/spring pressure into seat setup. And I don't care how good the valve is, it won't keep oil pressure in the engine. All it does is keep oil in the filter housing from draining down. I would usually suspect the individual components like the vanos, timing chain tensioner, HVA units (hydrolic valve adjusters, [lifters]), etc. bleeding down. Mainly I would suspect that the vanos units could have the oil bleeding out overnight allowing movement/clatter in them until they are pumped up again a few seconds after startup.

What weight oil do you use to make it go away? 10W30?

This is what my tech buddy told me happens as the engine ages.