I like blending as straight synthetic can be too expensive, for example my truck takes 3 gallons and due to warranty I can't extend oil changes.
But, I also find that synthetic seems to clean better than straight dino, where my first use of a blend fixed what I guess was a sticky lifter on a Taurus. The car had well over 100k miles on it, it was making funny 'chuffing noises' when giving it some throttle, and after driving with the blend for a short while I heard some clicking sounds that got louder and then quit, and then the car drove fine. We have over 170k miles on it now.
For the last oil change in my truck I used 3 qts of Mobil 1 Truck & SUV and 9 qts of Delvac 1300, a blend that works well. When I changed the oil in the older Taurus yesterday I used 2 qts of Mobil 1 Truck & SUV and topped it off with what seemed to be 3 qts of Delvac 1300. For the car I was more interested in getting close to a 10W-40, as the Mobil 1 is 5W-40 while the Delvac 1300 is 15W-40. The car has been burning more oil lately so I'm hoping the thicker oil will do better. I'm also hoping that the Delvac/Mobil 1, both of which are a HDEO, will provide even better cleaning. A small consideration is that if it works ok I can narrow my oils to two. But, it's an experiment so we'll see.