Going from mobil 1 fully synthethic to walmart oil change is bad???
 

I had gotten a mobil 1 oil change for $50 & my gas mileage was great then after the 3000 miles i got a $20 walmart supertec oil change & the mileage went really bad. 1 would get about 250 miles a tank on mobil 1 & on walmart it dropped to 180. Why did it make such a huge difference???















BTW i drive a 2002 honda civic sedan with 76,000 miles & i use the 5w/20 oil.

Mobil 1 has very good lubricating ability so you have very low engine friction and wear. So less HP uses just to run the motor so car uses less gas. Walmart oil is not so good.