Q: Seems like I'm losing mpgs or burning more gas after oil change

asked by on August 10, 2017

I had an oil change about a week ago and now it seems like I'm burning more gas than it's supposed to and not getting the mpg like the car came with when I purchased at the dealership. They replaced the engine filter topped everything off and a few days later it was starting to hesitate when I step on gas after leaving red light so I took it to dealership to get a possibility of what it could be they said not sure but they told me to drain oil to fill mark because it was overfilled so I did that but it's still feels like I'm not getting the MPGS or conserving fuel. Can someone please help with this? Thank you. Adam

My car has 126158 miles.
My car has an automatic transmission.

Depending on the engine oil viscosity that was used when changing your oil, you may have a thicker oil than what is recommended causing the drop in fuel mileage. All things being equal, fuel efficiency is determined by the relative viscosity of the oil used, as well as how easy they pump during the warm-up phase of an engine. For every +/- 10% change in viscosity, you can expect a fuel efficiency difference on the order of 2%. As an example, the difference in fuel efficiency between an SAE 5w-20 and 5w-40 would be about 4%. You may want to determine what oil was used in your last oil change as this may likely explain some of your variance in fuel mileage.

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