Could be lots of things in order and assuming it's a petrol engine and noise goes once engine warm.
Sounds as if oil is slow in getting around the engine.
Have you checked engine oil level
When was oil last changed- correct grade
When was oil filter last changed and has oil filter got none return valve.
Partly blocked oil pick up strainer in sump
Worn oil pump
If noise still there once engine is warm then may be a worn camshaft.
Check the above and see if any improvement
M
December 2010