I am in Rapid City SD. I am trying to find out if it would be safe to use 85 octane as they sell it here. Any inputs??

 

From my area the lowest i see is 87 and i run 89...but it should be safe you just wont get as good gas efficency as a higher octane

 

85 seems abit low. the lowest they have around here is 87. I wouldnt advise you putting in 85 octane. your motor will probly start knocking when you put it in. and how much cheaper is 85 compared to 87.

here, gas just went upto 91.9/liter for 87 and like 1.06/liter for 91

 

probiblya lot carbon build up from that low of octane

 

how mush cheaper is it, there is always pour in octaine boost if it comes out cheaper with puting that in....

 

Its not about being cheaper. The reason they sell 85 here is because we are over 3000 feet above sea level. I have been told it would be ok. I don't like mid grade here because they use 10% ethanol. And, I am too cheap for premium.

 

higher altitude means less oxygen which means richer mixture, so you can get away with lower octane. Besides, lower octane burns easier so an engine running properly should burn more efficiently with lower octane. Higher octane doesn't equal better fuel economy with all things being equal.

Run it, if you're not pinging then it's fine. If you are, keep your foot out of it until you can raise the octane upa bit.

 

higher altitude means less oxygen which means richer mixture, so you can get away with lower octane. Besides, lower octane burns easier so an engine running properly should burn more efficiently with lower octane. Higher octane doesn't equal better fuel economy with all things being equal.

Run it, if you're not pinging then it's fine. If you are, keep your foot out of it until you can raise the octane upa bit.

 

Not that i dont belive you but wouldnt less oxygen mean the computer would send less fuel to the engine to keep the same fuel to air ratio?

 

I've been running 85 octane in both Utah and now Colorado for 4 years in my Durango (5.9)and 2 years in my Dak (4.7)with absolutely no problems.