what gas do you run?

[MTMike]

My 383 won't run on anything but premium either. It doesn't like anything lower - it's got pretty high compression.... higher than 10:1

It especially hurts when it only gets 4-5 mpg

 

[redneckdude]

87...the motor was meant to run on it, its still almost totally stock and does perfectly fine on 87 so thats what it gets...

the caddy im drivin currently has to have premium tho...but gets 18mpg in the city, 26 city and has almost 300 hp to the wheels

 

[boggerless]

87 junk TJ.

 

[guido666]

Cheapest possible,,,,,with a truck getting 10 gallons per mile,,,

I get 4 MPG in the city! Haha

 

[CyberSniper]

I can't run 87. Way too much pre-detonation.

Everything I've had has always gotten better gas mileage with 89 octane than 87 octane... enough to warrant the extra nickel/gallon. Usually it's only 1-1.5mpg but it's enough where it makes up for it. Not to mention the performance is 100x better. On today's modern vehicles with always changing spark timing it probably isn't a big deal. OBDI and older, it is. If your motor is always running little to no advance you're wasting a lot of power/efficiency so 87 octane isn't always the way to go.

However, I've never found enough (if any) increase between 89 octane and 93 octane to warrant the cost increase. I do run it quite often though, mostly because where I buy a lot of my petrol is where they either sell 87 octane or 93 octane. Plus, I don't get the spark knock at light load like I do with 89 octane. I miss back home where you can get 86, 87, 89, 91, and 94 at the local Sunoco.