BAD GAS MILEAGE SINCE OIL CHANGE!!!!!?

I have a 1999 SAAB 9/3 and until a week ago the gas mileage on it was consistently 20.1 mpg using the information display (SID) . However, after I took it to firestone for a oil change the gas mileage dramatically dropped to 12.3 mpg! After a few days of seeing a consistent 12.3, I went to talk to the mechanic who changed the oil and he said that he didn't do anything and oil changes have no affect towards gas mileage.

I'm sure what I should do next..I'm really concerned.

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  • Anonymous
    10 years ago
    Favorite Answer

    Oil changes cannot and will not have any impact on gas mileage. Did you reset the SID to see if resetting it changes it? Has anything else changed that could have impacted your gas mileage?

    Something else is impacting it... your mechanic is telling you the truth. For example, a dirty air filter can badly impact your gas mileage - has the car been tuned as it should be?

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  • 4 years ago

    Oil is the blood in ur car n should b changed every 3000 miles, specially since it's from 1988. R u carrying lots of dead weight on ur truck? R u accelerating more than usual after a red light? Any truck/car/SUV w/ a proper tune-up will run better n increase ur gas mileage.

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  • jamzm
    Lv 5
    10 years ago

    Maybe you're looking at battery voltage and not mileage.

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