Thanks to all who replied. In the early seventies I was a VW line mechanic and engine rebuilder, worked at a dealership for a while so I know about changing oil but a friend said I should run straight 40 weight oil in the vehicle since it had 96,000 miles. The vehicle doesn't smoke, leak or appear to use oil for the past 60 days that we have had it and what my friend said didn't make sense to me so that is why I made the post. Also I was curious about a good make of oil filter and that was answered well. Since there is a long delay to when a message is posted, I changed oil before any of the replies came in because I needed to. I used Castrol 10w 30 oil with a Fram oil filter. I marked my calander for the next change at which time I will buy a NAPA gold filter or Wix and consider synthetic oil of the same weight.
Thanks again, first pickup I ever owned and the first GM product with the exception of my first vehicle, a 1950 Chevy automobile, automatic transmission (first year for automatic), purchased in 1957.