I have a left over 2011 SCREW, ECO, was talking to an owner of a 2012 ECO he was saying that when he changed oil (Mobil 1) he lost 3 or 4 MPG, stated that he went to Ford and they changed back to MotoCraft oil and he got his mileage back does this sound like something mythbusters should check out. I only have 6,000 miles so I want to do the right thing when I change my oil.

 

Even if the oil is a higher weight I seriously doubt that could possibly happen. Changing brands of oil would make no difference.


Edit: ok I did read where that can happen...so I guess I was wrong. It said it could be up to 1 to 2 percent loss. A car designed to use 5w30 will lose that much when going to 10w30. There are plenty of people that use a thicker oil in the summer than th do in the winter for added protection due to thermal breakdown. I have just never experienced a loss from just using oil...because milage is so subjective.

 

I've actually changed from MC oil to Mobil1 and back to MC oil after a long period of time on two vehicles and never noticed one bit of a difference in my MPG's.

 

Maybe they used 85/140 gear oil ! (lol). As long as the oils were close in weight rating and spec I would say the mileage would not change by the brand of oil used.

 

I don't think that's true. He is talking about a 25% drop in mpg's, very very unlikely.
I changed to M1 5W-30 at my first oil change (did it at 3,500 miles as I was about to tow for the first time), and I have seen no change in fuel consumption whatsoever (I have 1K miles on it with the M1 oil now).
I say myth, something else must have happened.

 

I would question the oil weights used and driving habits after the change.