[Stocker]

Synthetics should flow better when cold and offer better protection at higher temps. Nothing wrong with dino, it has worked well for a hundred years or so, but IMO synthetic is an improvement. Can't say which brand might be better so pick one you like (I'm running Mobil-1 75W-90 and have also used Redline). Only downside is synthetics cost a bit more, but you're only looking at a few quarts that will last you a few years or so.