For years I did't have to think about oil choices. I stuck with Castrol GTX conventional motor oil. I got my 5.8L, 1994 Ford van up to 260K and I figured I was good. I didn't have to think about oil at the BITOG level. Just buy it and change every 3k, using a Napa Gold filter. Now, according to Castrol, the 5W30 GTX is called GTX Ultraclean, and it's a blend. I don't know if want to "clean away the old sludge" from my engine. It could be holding stuff together. So, stick with dino, like Chevron Supreme, or make the switch to some high mileage juice. Conventional has got me this far, so do I stick with it? I might be living in the distant past. Oil tech might have come a long way and I should just try some sort of blend or full synthetic. The couple of bucks price difference is no big deal.