Can the full synthetic schaeffers oil do extended drains better that the blend? It seems like it should be able to, but the TBN seems low for a full synth. I know that the exact drain interval needs to be considered on a case by case trend oil analysis. However, would the full synth hold up better than the blend? If so by how much? What do you folks think? I'm also very impressed by the HTHS of 3.8 on the full synth. That's the highest I've seen on any spec sheet for a xW-30 weight oil.