I concur whole heartedly.  This has been my experience as well.

______________________________ Reply Separator _________________________________
Subject: Re: Oil light befuddles me.
Author:  vanagon@lenti.med.umn.edu at SMTPGATE
Date:    4/7/97 11:12 PM

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Yes! This is the second message of a similar vein I have replied to 
this week. The 10w30 does not "hold" enough pressure when hot; 20w50 
will work fine. Some say this is due to worn crank bearings/journals, 
but all I know is I have put 100k on my TD engine since first having 
this problem, with no signs of trouble. I installed a mechanical 
pressure gauge and saw a difference of up to 10psi between 10w30 and 
20w50 when hot, measured from the cylinder head sensor location.
     
---snip