well tittle says it all just wondering if the good ol regular is good or mid-grade? or what do you put in your tank

 

Owner's manual will suggest, but regular would be just fine.

 

IN both of my 4th gens (a 00 Z28 and a 99 V6) I found that mid grade was the best for the money. I didnt get any noticable mileage or performance improvements from mid to high grade, all I did notice was less money in my bank account. There is a noticable difference between regular and mid in both performance and mileage. It is worth the extra $.10 per gal but not the $.40 more for high grade.

Massey

 

thanks!! I went with mid grade

 

Your 3.4 has a 9:1 c.r., and GM recommends using 87 octane. The only real difference you're likely to notice, is having a lighter wallet. As in Massey's case, the 3.8 has a 9.4:1 c.r., and 87 octane is still the recommended fuel. But I'd consider that borderline where that engine might benefit better from using mid grade.