Not for seldom used engines....
Synthetic oils do lubricate very well, and were originally invented for jet engines operating in below zero cold air. *The synthetic oils don't thicken. Because of it's great anti-friction qualities, that's the reason not to use synthetic oils during engine break-in.The problem with synthetics is that the synthetic oil slowly drains-off engine parts in a shut-down engine. Mineral oils maintain an adequate oil film much longer than synthetics. What that translates to is with synthetics, if you haven't fired-up your engine for a couple of weeks it will be a "dry start" until the oil starts pumping. So...if you run your engine very often, synthetics are probably okay. If you only start your engine every couple of weeks, don't use synthetic oil or you'll be needing rod bearings much sooner than expected!