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Has anyone noticed a huge difference in performance using 93 octane Premium over Regular 87 octane?

Oneyed1
 

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Oneyed1 said:
Has anyone noticed a huge difference in performance using 93 octane Premium over Regular 87 octane?
Other that the increased price?

Most Prius owners notice lowered MPG (less BTU content in higher octane fuels), and several get check engine lights (usually engine misfire codes).

The US owner's manual says to use 87 octane ((R+M)/2 method), so use that.

I highly suggest that you read "The Low-Down on High Octane Gasoline":
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm
 

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Oneyed1 said:
Has anyone noticed a huge difference in performance using 93 octane Premium over Regular 87 octane?
I noticed a big jump when I switched octane to Shell V-Power from Chevron. I was playing around and thought I'd try it. Mileage went from 40 to 48 mpg, even seeing 52 for a while which I never saw on the display before. I tried the Shell lower grade next round and mileage still stayed around 48 mpg. Big drop came when I went back to Chevron as it dropped all the way down to 38 and now is climbing back up to 44 mpg.

It may having something to do with the formulation or ethanol mix for winter. California likes to play with their gas a bit. I think they are into some phase 3 design now called CaRFG#3 or something. Switch usually happens in October, but I recall reading where the governor signed some law about delaying the change so the hurricane refineries didn't have to spend time reformulating gas for all regions (something like 35 different blends?). Maybe they have and the switch to the winter grade has began?

Dunno, but changing around has caused me radical swings in my mpg ratings - both brands and octanes. All I know is a little change shows up as a big difference on the display. I doubt if I would have seen much of a change in the gobbler I had prior. A 10% fuel formulation change on a 15 mpg vehicle doesn't appear as significant as it does on one getting 50 mpg.
 

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G. McCurdy said:
Oneyed1 said:
Has anyone noticed a huge difference in performance using 93 octane Premium over Regular 87 octane?
I noticed a big jump when I switched octane to Shell V-Power from Chevron. I was playing around and thought I'd try it. Mileage went from 40 to 48 mpg, even seeing 52 for a while which I never saw on the display before. I tried the Shell lower grade next round and mileage still stayed around 48 mpg. Big drop came when I went back to Chevron as it dropped all the way down to 38 and now is climbing back up to 44 mpg.

It may having something to do with the formulation or ethanol mix for winter. California likes to play with their gas a bit. I think they are into some phase 3 design now called CaRFG#3 or something. Switch usually happens in October, but I recall reading where the governor signed some law about delaying the change so the hurricane refineries didn't have to spend time reformulating gas for all regions (something like 35 different blends?). Maybe they have and the switch to the winter grade has began?

Dunno, but changing around has caused me radical swings in my mpg ratings - both brands and octanes. All I know is a little change shows up as a big difference on the display. I doubt if I would have seen much of a change in the gobbler I had prior. A 10% fuel formulation change on a 15 mpg vehicle doesn't appear as significant as it does on one getting 50 mpg.
If the test noted in the blue paragraph above was only done on one tank of gas, then it's not likely a very accurate test. You need to measure it over 3 or 4 tanks of gas in order to reduce the mathematical errors that can occur during filling.
 
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