Like many listees, I have occasional noise from a sticky lifter.  It used 
to only manifest itself occasionally when I started-up and always went 
away and stayed away by the time the engine warmed up fully.  I also used 
to only use the van for long freeway trips.  For the last year I have 
been using it as a daily driver, only 4 miles to work, all uphill and the 
engine doesn't fully warm up on this short trip.  Recently, I have been 
hearing the sound more sporadically, it still goes away after warm-up but 
sometimes I hear it after slowing down from freeway speed (when the 
engine has been warm for quiet awhile.  Then, it goes away after a bit of 
slower city driving.  I wonder if simply more dirt has accumulated (if 
this is actually the problem!) and would some long freeway trips at least 
reduce the noise to the way it used to be.  I also wonder if it is time 
to replace the lifters.  I'd rather not (quoted ~$500), but I'm wondering 
if I am risking damage.  Is this a familiar story to anyone?  I also 
looked at an oil additive (Justice Bros brand, to free sticky lifters and 
valves, $5. for 11oz can).  I think it is just liquid detergent suspended 
in oil.  Has anyone tryed this type of product?  The person I spoke to at 
my FLAPS  said it may or may not work, but either way it wouldn't cause 
any damage.  I was zen about this noise before, when it always 
predictably went away, but now I'm obsessed!  Also, if I were to replace the 
lifters, should I have the valves or anything else done while the engine 
is open?  Well, I think I just used up a months worth of questioning 
privileges

Charles
'83.5 GL Westy