Gas mileage all over the place

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Mar 17, 2018 | 05:51 AM

Bluegoose95401

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Joined: Nov 2017

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Gas mileage all over the place

Ok so my gas Mileage is all over the place when I first got the car i went three tanks at a steady 30 miles a gallon then it dropped to 25 then the next tank was 15 then the next was 13 then the next was 12 tonight I went and filled up it was back to 26 mpg. Just did cap rotor wires and plugs ( old plugs looked fine little brown like a lightly toasted marshmallow ) . Do you think it’s the quality of gas usually I get 91 octain from rotten Robby but do you think i would be better off with 87 or getting gas from chevron. Or even 91 octain from chevron?? Possibly somthing else like a clogged catalytic converter. It’s a 3.1 90 bird sorry for the rambling.

Mar 20, 2018 | 08:28 PM

JA411

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Joined: Aug 2015

Posts: 117

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Re: Gas mileage all over the place

Use a quality 87. Compression is not high enough to support higher octane. It will just cause unburnt fuel, excess carbon build up, and even get into spark knock with the carbon. I have a 2nd, 3rd and 4th gens. The V6's work best on 87!
JOE