Sorry Jeremy I missed your post. From that which I have only read, it is possible that during the process of changing both the oil and filter can be enough for the oil pump to loose prime..?
Thus when I change the oil in my +8, I fill the new filter with oil prior to fitting, which makes a bit of a mess when trying to screw it back in place, but it has worked well in the oil changes on my old +8 for over 20 years.
If you fit a dry filter, then I imagine that the oil pump has to have enough suck to raise oil from the sump, into the filter to fill it, before the oil reaches the pumps gears to then be pressurised into the oil galleries before ending up draining by gravity back into the sump to repeat the process...?
When an engine is shut down the oil is thinner, thus gravity can have an effect and perhaps more so over time, draining oil from the galleries and pump over time resulting in a rattle at start up..
Some oils seem better suited to regular lay up than others, as engine design altered in time and older type oils may be difficult to find.. I think Castrol Magnatec was a advertising campaign, suggesting the oil stuck to bearings etc better than other oild to provide lubrication on initial start up, which supposedly other oils may not..?
If the oil pump has worn due to poor oil quality, the possibility of crud being sucked into the gears, or the filter clogging due to irregular changes or even the filter it`s self perhaps being some sort of cheap counterfeit part that has caused some oil pump starvation and thus damage...
My guess was that trying to prime the pump, was just the simplest of processes to try first.
Still got my fingers crossed..
