My father's daily driver is like new 1976 Chevrolet Chevelle coupe, with a mere 80K on it's 350 2BBL engine. Although the car is his only driver, as you can tell by the mileage it isn't used very much. Later this week I will be visiting him, and he asked if I could do an oil change on his car. So, now I have to decide what oil to use, which isn't such an easy decision. He has been using either Castrol or Pennzoil dino for the last few years. This has worked fine, but quite frankly I'd like to run something a little better (especially since I will likely acquire this car some day). I also wanted to run an oil that would offer the best protection for the flat tappets and cam. The car is also mostly used for shorter trips now, although it may see the occasional light highway trip. That said, I think a high TBN is important, especially since this is a carbed engine. I was thinking of switching him over to a 10W30 HDEO. I don't want to run a 15W40 since the car is used during the winter months, and it is far too thick. One readily available 10W30 HDEO is Esso XD-3, and this was the choice I was thinking of trying. I also might be able to get Chevron Delo 10W30, since their is a Chevron dealer in his city. My dad is too old fashioned for synthetics or extended intervals, so that is out of the question. So, is a 10W30 HDEO my best choice for this car, or should I just stick with plain old Pennzoil dino? Does anyone have any experience with Esso XD-3 oil? Any comments appreciated.