I have a 97 GST Spyder and was wondering if I could run Mid Grade gas or can I only use premium, (93 octane)??

 

depends...in winter... mid grade is fine... summer... sometimes mid grade is ok... sometimes not... but you do get more power out of the high grade... The only difference is that you will notice is that when the engine is stressed the engine will knock.

 

I always use the high grade, I think it is much easier on your engine if you do so.