This is the gospel according to Blackstone.
I ran Castrol Act-evo 10w-40 up to 16,257 miles and sent a sample to Blackstone. This oil had 4,033 miles on it, and according to them, It was pretty much shot. It had degraded to a 10w30 and the TBN was a 1.0. Not good!
I ran a 3000 mile flush of Amsoil and then put 4000 on this change and had it tested. Although it beat the Castrol, it doesn' look like there is such a thing as a long distance motor oil for bikes. Looks like wear was about the same, but the TBN was 3.8( some active additive left) and the viscosity was 69.6. Still a 10w40. Blackstone says go ahead and change at 4000. I can go along with this frequency but I can't believe Honda oil can stand up to 8000 miles like they recommend. I wish someone would do a 4000 on Honda oil.If I can get it on, below you will find Blackstones's report.
Sorry, I can't figure out how to send Blackstone's report, some body help! I can change oil better than I can run this dang computor.
Robin