For sure synthetic oil is better than conventional. But I don't need it! I live in California where it doesn't get very cold or hot. I don't drive in difficult conditions, most of my driving is on the freeway at 70 mph. I change the oil and filter on my 2006 Forester as Subaru recommends. I use OEM filters because as long as I keep up the maintenance it don't have to worry about the filter even getting close to being clogged. So a low bypass setting doesn't concern me.