Yes, you can continue using your old red Fuel Saver card, but you will only get discounts on fuel. But if you discounts on groceries, you'll only be able to take advantage of them if you link your new Hy-Vee Fuel Saver + Perks card or sign up for the service on your Hy-Vee app or at https://www.hy-vee.com/perks.