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Q: My gas mileage dropped after an oil change.

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I was getting 36 MPG for months regular driving and even got 42 for the duration of a road trip. After I got my oil changed, I never get my MPG above 32 again, usually not even above 31. I bought conventional oil. Would synthetic oil have prevented this issue? Or is the oil unrelated to gas mileage? This was the first time I've had the oil changed and I don't know what kind the previous owner used. I've been fueling with premium gas the whole time I've had the car. I really want my economy back to the way it was.

My car has 60000 miles.
My car has an automatic transmission.

If you were using one type of oil and then replaced with a different oil that does not meed specifications of the motor by being too thick then it would affect fuel mileage by maybe 1 mpg. If you are loosing more than this then look elsewhere. Check tire pressures and filters. If still having issues then have vehicle checked.

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