My wife has a 2015 Subaru Forester we purchased used in 2016 with about 11k miles on it. The first few oil changes were either completed at a Subaru dealer or by an oil change service using Pennzoil Ultra Platinum. I eventually began completing the oil changes myself using either Mobil 1 or Pennzoil full synthetic.
In late 2017 my wife purchased the oil for her oil change and I didn't actually pay attention to what she purchased. She had purchased the high mileage version of Pennzoil synthetic. Her car that had previously gotten 25 to 27 MPG immediately began getting only 22 MPG during the same exact type of driving.
I changed the oil again within a month or two and changed it again after just a few months and the poor gas mileage persisted. I have changed it 2 or 3 more times since then and the poor gas mileage still persists.
Is there anything I can do to safely clean out the engine of any residual material from the high mileage oil?
Thanks very much in advance.
In late 2017 my wife purchased the oil for her oil change and I didn't actually pay attention to what she purchased. She had purchased the high mileage version of Pennzoil synthetic. Her car that had previously gotten 25 to 27 MPG immediately began getting only 22 MPG during the same exact type of driving.
I changed the oil again within a month or two and changed it again after just a few months and the poor gas mileage persisted. I have changed it 2 or 3 more times since then and the poor gas mileage still persists.
Is there anything I can do to safely clean out the engine of any residual material from the high mileage oil?
Thanks very much in advance.