If you just need to "get by" until you do a flush and change by topping off, the safest things for you to do right now is just to add some Distilled water. Its not going to dilute the coolant by enough to change the efficiency of it and will buy you a little time to do it right. I would change to G05. Its retro compatible and represents the newest technology and advancements. Most manufacturers are going to it.
I went with Zerex G-05 HOAT out of an abundance of caution, 2006 TJ Rubicon with 40,000 miles just because it was seven years old and never changed. Available here in Virginia at O'Reilly's Auto Parts, $18 @ gallon (of course, you need 1.3 gallons!) Drained system, filled with distilled water, drove to operating temps with heater box on high in the July heat, drained system, filled with distilled water, drove to operating temps with heater box on high in the July heat, drained system, refilled with 50% HOAT and 50% distilled water.
Extended highway driving, city traffic, eight miles of 4-LO offroad rocks, a thousand miles later doesn't matter Coolant Temp Gauge locked onto 210 degrees. Peace of mind: priceless
If NAPA doesn't have it on hand, check if Grainger has it.. I get my Zerex there and it's a few bucks cheaper
Amazon.com will ship you a gallon of G05 for $20.19 straight or $18.57 for 50/50. That may or may not be a couple of bucks more than NAPA or whatever, but it's pretty convenient for the brown truck to bring it to your door. Spend a few more bucks at Amazon to bring the total order to $25 and get free shipping.