I was quoting that July 2017 Blackstone newsletter...
"Shell Rotella T6 had the lowest iron wear rate, at 2.03 ppm per 1,000 miles, while Royal Purple 5W/30 had the highest wear rate, at 2.58 ppm per 1,000 miles. The difference is just over half a part per million per 1,000 miles, which is almost completely negligible. In a typical engine, a half a part per million of the oil in the sump is such a small quantity that you wouldn't be able to see it without a microscope. To put that in perspective, an Olympic-sized swimming pool holds about 660,000 gallons of water. One half part per million of that volume would equal just over 5 cups of water - that's like mixing half of a 2-liter bottle of Sprite into the pool, and it makes about as much impact on your engine: if you know it's there, it might bother you, but realistically, you'll never notice the difference.....
Now, some people report better fuel economy or other benefits from using one type of oil instead of another, and if that's you, that's great. Our point here is not to tell you that you should or shouldn't use a certain type of oil, so by all means, feel free to stick with what's working for you. All we're saying is, if you want to try an oil that maybe costs a little less, you probably don't need to worry about it causing any problems. Send us a sample of what you're using, and then try a similar oil run with the new stuff - by comparing those results, you might find that you can get the same great results, and save a little money as well! Good luck! "