CafeRacer

Hi again.
 
I just gave it an oil and filter change in the hope that the PH-16 would fix the knocking via its internal non return valve.
 
I think you may be right about it possibly being a delay in the valve clearances being taken up by the oil pressure. That would explain the need for having an oil filter with an anti-drain valve fitted ?
 
I will continue to seek out this magic filter and if it turns up I will let you know...

Ah ok, could it be a delay in the valve clearances being taken up with oil pressure? A mate of mine has a 3.2 V6 Omega that does that quite loudly, sounds awful for about 30 seconds from cold then sweet as you like there after.
 
I have a small rattle (not big like yours) which all I can finally come up with is the cam chain. It's silent on start up, gets a noise, goes silent, then after probably 10 seconds settles into a light rattle, which goes away if you raise the revs very slightly.
 
Have you done an flush oil change? Either with flushing additive to the old oil or as I do using actual "flushing oil"? It might help clear any muck delaying the filling of the valves.
However - it may also do more harm than good depending on how well the oil changes have been treated in the past. If it's really mucky don't use it first time, just do a good oil change (or 2).