Hyundai is pretty liberal in what oil you can use.
Your Elantra can use almost any SN rated oil, conventional, synthetic or blend and will be just fine.
I am guessing you have the 2.4 (5w-20 on the cap), and the manual (page 8-9) says you can use 5w-20, 5w-30 for any temperature, or 10w-30 above 0°F.
If you had the Turbo, you could use 5w-30, 10w-30, 5w-40, 15w-40 or even 20w-50 in temps above 20°F.
Oil needs to be API SM or above / ILSAC GF-4 or above / ACEA A5 or above, which the Valvoline is.
Quaker State is just the "recommended oil" because the 2 companies get kick backs from each other I am sure (although my moms Kia Soul has Total Oil listed in the manual).
The Soul has the same 2.4 motor as you and I plan on using 5w-30 or 10w-30 oil in it for the rest of it's life.
I think you will find quite a few Kia and Hyundai owners running 5w-30 oils in the 2.4 with no issues (and no issues with 5w-20 either).
Drive it and don't worry about it. If you want to be like most here, change the oil at least every 5,000 miles (the Hyundai GDI engines can have fuel dilution issues). My Santa Fe and Mom's Soul are on 5000 mile intervals. My sisters Santa Fe is on a ~7,500 mile interval (she does mostly highway).
If you do mostly highway, 7,500 is fine.