I use 93 in mine at last fill up was $3.49 a gallon. It lasts me about a week, and the winter kills my mileage as usual.

 

87 for the win!

 

Used to run 87 now 93 in my 3.8 NA, getting my PCM flashed in the spring.
$3.10 ish gal.

 

I just bought a 2003 LS 3.4; I put a couple of tanks of 87 in it, and got an intermittent engine light. I switched to 89 and no more engine light.

 

It's interesting... My Monte has 194,000km on her and I had a fuel line flush & clean done at 165,000km... The mechanic told me that it is rare to see an engine as clean as this one, the flush cost me $160.00(CDN) and was not necessary... I wonder if the High-Octane fuel really does keep it cleaner with additives or maybe burns hotter?...

 

Please tell me you are kidding. You paid 160 for a "fuel line flush"? Fuel injected engines constantly "flush" the lines themselves. There is a return line that runs back into the tank so every time you run the car, you are "flushing" the fuel lines. If they charged you 160 for that then they just stole 160 from you.

 

Unfortunately, it's true (thinking back it might have been $110.00 with an oil change)... I got it done at a local shop that I nolonger frequent... I guess you live and learn, this lesson was a little on the expensive side for my taste...... The info you provided is good to know...... Thanks,

 

Here in NJ our choices of octane are somewhat limited - I believe it's 87, 89, and 94 for the most part. I remember when I lived in NY many years ago Sunoco used to have something like six different choices ranging from 86 to 94. I believe they included 86/87/89/90/92/94. Since putting the L67 in, I stick with 94.

 

87 Octane which is recommended by GM. Use what makes your car run at its best. I do dry gas when winter bgins then dry gas in the spring to keep moisture out of the tank.
Change the fuel filter every 15 k.

 

I always buy 87 octane regular unleaded for my 3.9L Monte and it runs great on it. Last week, the cheapest regular unleaded locally was going for $3.279/gal. I spend a lot on gas as it is.... just under $2100 for all of 2010 (which is a new high for me), so why would I want to spend any more than I have to by buying a higher grade than I need?