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What grade gas?


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What grade should I be using on this 1985 2Dr Hatchback, Carb 1600 Ea81? I am getting 28MPG now using regular unleaded. Would I get better than that, and would it increase performance if I used Premium gas? The book says 91 octane and I have been using 85. When I bought it the guy told me he used regular unleaded so I didn't change. So what are you getting for MPG and what grade of gas?

I have been told also that higher grades in high altitudes is bad for the motors.

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i wonder why the owners manual says that for your engine. with the price of gas id stick with regualr. that mileage sounds low to me, i got 36 mpg on a good day out of my wagon.

 

The manual may not be a US one. Octane can be measured in two ways, Both japan and New Zealand measure it differently to the US. ie our regular is 91, premium is 96.

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the 1985 buyer's guide spec's 90 or higher (us method) - I run midtest (89) and get better performance/mileage than regular (87) by a 2-3 mpg difference - has always been that way since new - runs like a dog with regular - however I don't mess with premium - wayyy too expensive

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Thanks for all the input. I used to own a 1990 Chevy S-10 that ran like caca with regular in it, but ran great with the mid grade. I might try that with this machine, but I am worried that after running regular in it all it's life and then changing will hurt it. I was told that high altitudes and higher grade gas can harm engine components.

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High altitutes plus high grade might make it seem sluggish, as the air is less dense and the fuel burns slower. Essentially, you'd be running rich. I don't think that would hurt anything (converter temps might be higher).

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