Either Valvoline product should be fine for normal drain intervals (i. e. 7. 5K). But if you plan to get full value from a by-pass system, you should go to a full synthetic for extended drains. While the PB2000 provides some of the advantages of a synthetic (better flow properties, lower engine deposits), the conventional component of semi-synthetics oxidizes just as quickly as with a regular oil. The additive package should also be fortified for extended drain intervals. Delvac, Amsoil, Royal Purple, and Redline market synthetic oils that are designed for longer drain intervals. LE and Scheaffer sell fortified conventional based oils that are specifically marketed for extended drains. Just remember that the whole bypass filter/extended drain principle was developed for OTR trucks. Oils do not hold up nearly as well in a daily ride that is used for short trips regardless of the oil base and filtration system that is used.