While Infinity tells in owner manual to use Premium (91 AKI) gas will Plus (89 AKI) hurt the engine? Or it will cause degradation of performance only?
What!! I'm pretty sure that if it's discovered you've been pumping regular unleaded into your tank, any warranty claims could (and likely would) be denied. Not to mention engine knocking. It clearly states on the tank cap as well to "Use Premium Unleaded Only".