I heard a rumor that the blended syns (I used valvoline durablend) are nothing more than very very pure Dino oils. And they dont actually contain synthetics at all. But this is only someting I heard around the campfire. I know that I switched from Durablend to Mobile 1 and the engine had the same leak as it did before. Its the older engine oils, and the seals that are conditioned by them that have the leakage problem. My 85 accord went 185,000 on regular oil before I switched over to mobile 1 and it had zero leaks before, and after the change.
