@Owen Lucas - you got several easy options:
- stick with synthetic 5W-30
- go with High Mileage 5W-30 (not my favorite as each manufacturer has his own definition of what constitutes high mileage)
- go with a 0W-40 which is essentially a thicker 0/5W-30 due to how modern 0W-40 oils are formulated
- or you can always try to defy the odds and go with 0W-20 - and if you choose this route, then please post at least one or two UOAs so we can all see if the drop in viscosity has any measurable impact on your engine
If you choose to go with 0W-20, nothing spectacular will happen. Most likely oil consumption will increase, as well as your wear rate. But your engine won't go bad overnight, it will struggle for a long time on that thin oil before it gives up the gost, if ever. The difference between fuel economy ILSAC oil viscosities is pretty small, I would say borderline insignificant, to the point that 5W-20 has become irrelevant and 5W-30 only exists to provide an alternative oil with better NOACK and flash point for certain turbo charged engines. Even those are slowly moving to 0W-20, just look at the Toyota Supra.