rpd im with you ive been putting 87 in my 04 mc and she is at 75,000 miles strong with 27.5 mpg city

 

i usually run 89 in my monte except when i go on trips...then i usually run 93. my monte runs a lot better on 93.

the highest mpg ive ever had was about 35 (during a trip). i usually get between 30-32 with 93 on the highway.

 

our cars have been designed to run on 87 octane. how gas works is the lower the octane, the quicker the gas burns, in which can cause knocking and pinging on a heavy load. with the advent of the computers that control how the engine runs, a lower octane fuel can be used. if the computer senses a knock or a ping, the computer then retards the timing until the knock goes away. on the other hand, a higher octane fuel burns slower than a lower octane, but the burn is hotter and makes the engine produce better mileage and a little bit more power. some manufacturers only recommend a higher octane fuel to be used in some of their higher performance engines.

 

i certainly agree cause the 85 -88 models is my dream car. i am going to fully restore one once i get my 04 monte paid for.

 

my bad lol i use 87 here in atlanta

 

I used to put in mid grade -89 but when the gas prices went sky high I switched back to 87 and I can't tell any difference, so I'm sticking with the cheap stuff. I usally buy from Shell or Marathon. I don't drive the car that often but it gets around 20-22 mpg in the city - I only do crappy gridlock city driving and no highway driving.

 

I run all it needs, 87 octane

 

Alright, I have had my '06 SS since May and had been running Regular. The 5.3 does not require the higher grade, therefore I saved the money. However, after reading this thread I gave it a second thought and tried Premium two weeks ago. There is a HELLUVA difference! The reaction time is drastically improved and it seems to run a LOT smoother. Having driven the same vehicle trying both grades, I have come to this conclusion: yes, it is alright to drive with Regular, but damn does the premium make a difference in the driving, and for the extra $3 a fill, its worth it for me, I didnt spend that much damn money to short change myself by not giving it the best she deserves. RUN PREMIUM!