I've had my 2010 WRX for about a month now. I've been filling it with premium fuel, or so I thought! I have the app Gas Buddy on my phone which compares gas prices relative to your location. Shell always had the lowest price, usually by 10 cents. Well I just realized tonight its because its 91 octane fuel and not 93 like the fuel at holiday or other competitors! What an idiot! Anyways, I'm wondering if the difference from 91 to 93 is going to be noticeable and if I'm truly depriving my engine from the 93 octane it needs.
Basically, should I stop filling the tank with 91 and fill with 93 and if not, am I hurting the longevity of my engine? Thanks for your responses ahead of time!