Vermonter
 

My 2009 XD has 56,000 miles and when started after sitting as short a time as 30 minutes, has an engine knock before the oil pressure builds up. I have heard this sound in other vehicles when it was necessary to mount the oil filter dry--horizontal filter. Could it be that this vehicle's filter is draining out as it sits? Has anyone else heard this sound and is there normally a check valve in the line on this engine, since the filter is horizontal? Any advice would be appreciated.