Probably means they had a bunch of oil to sell that was not moving well, so they added a cap full of synthetic oil to it so they could call it "part synthetic"and let marketing do the rest
My latest UOA results using HDEO (Valvoline Premium Blue 15w-40) in my ST came back with outstanding results.
Its still rated for use with Gasoline engines, unlike most of the Shell Rotella T stuff lately.
I'm even using it in the Primary on my Screaming Eagle Road King, and have very good clutch engagement.
I don't use it to save a few bucks, I use it because the UOA results come back with better results than just about all of the MC specific oils.
So if its watered down, and has less of the good stuff in it as suggested, why are the results still better than the MC specific stuff?