You're fine with 10w-30. If you're going to be in very hot summer weather then consider a 20w-40 but that's my opinion. Others are free to disagree and give their thoughts.

15-50 Mobil 1 to get the higher Zinc content to protect the cam & lifters.

hi     10/30 oil is ok,note my 79 c3 ran at temp  at 220   I installed 2 core alum radiator now on hot  days  my temp is 175 0    but you want cooler oil must have cooler rad temp  dwa

+1 more on the Mobil One 15-50 because of the higher ZZDP level !!

How about Vavoline VR1 conventional 10W30 ? I've been hearing thicker oil causes harder starts which can cause damage ?

I've alway been a fan of Valvoline engine oils. 

I use Joe Gibbs conventional, I think 10w-30.  The Joe Gibbs thing is for the appropriate level of zinc/ZDDP for a flat tappet cam, the conventional is because I don't think synthetic is needed or even a good idea for our motors (they weren't designed for it and synthetic may leak past the looser seal tolerances).  It's expensive, but I only change oil in my vette once a year.  

+2

Clarification on the Joe Gibbs oil I use: it's the hot rod oil, not the racing oil.  Not sure you'd want to use racing oil in our cars, unless you raced it.  

|UPDATED|3/22/2015 9:31:14 PM (AZT)|/UPDATED|