RN> I'm late (but still alive) in this thread and it sounds like a tappet   
   RN> noise.   
   RN>  I don't know if you have solid or hydraulic lifters, but if either is   
   RN> properly set, and I don't believe in "Mechanic in a can" although   
   RN> sometimes   
   RN> it can help.  So, you can try either Bardahl top oil or put a container   
   RN> of   
   RN> STP oil treatment in the crankcase and see if that helps.  It sounds like   
   RN> some blockage is slowing down the oil from gettting to the lifters.  The   
   RN> blockage could even be in the oil pump filter (Wow!  Is that and oldie!).   
   RN>    
   RN> I've been away from this stuff longer than Roy, but I'm a pretty good   
   RN> guesser.  (-:   
      
   Here is the story in 30 seconds or less.  :)   
      
   The engine has done this since day one when I got it - this spring.  It is a   
   Jasper new/rebuilt motor with a 3 year / 100k warranty.  It runs perfect, but   
   just has that tap noise for less than a minute on cold starts (after it has   
   been sitting for more than 5 hours).     
      
   Many say this is normal for many GM motors and not to worry about it.  If a   
   problem does happen, it gets fixed or replaced for free.   
      
   The type of oil I use doesn't seem to have any effect.  The warmer it is, the   
   less time it does it.  The colder, the longer.  At least that is what it seems.   
      
   It never does it longer than around a minute at the most.  Typically, around   
   30 seconds or so.   
      
   - Mark   
      
   --- WWIVToss v.1.50    
    * Origin:  http://www.weather-station.org * Bel Air, MD -USA (1:261/1304.0)