What Is the best Motor oil That Will give the Best Gas mileage.My last Oil Change Reduced my Gas mileage. By 5% or more Bought used So dont know What Oil Was in before.
What grade oil did you use on that oil change? A higher weight oil may reduce the milage, but 5% seems too extreme for just the oil. Of course, the cold weather that has hit most of the country is probably more guilty than the brand of oil you are using.
Unless you were using 80 weight tractor oil (don’t know if it even exists, but anyway) you’re not going to notice that much of a difference in gas mileage. Just use whatever name brand oil that’s on sale at your local parts store.
The only way to make sure you are reading the gas mileage correctly is to measure two tanks in a row from the same gas station, SAME PUMP, and stop at the first click. If you have measured a before and after accurately, and allowing for the colder weather, and you are absolutely sure your mileage has gone down, then you can look at the oil in the sump.
Generally, a heavy oil, such as a 10W40 oil will show slightly lower gas mileage than a light synthetic oil, such as a 0W30 or 0W20. These oils are extremely slippery and have “Energy Conserving” printed on the can or bottle. These oils will give you the best mileage, but they are problably not a good oil for a well worn engine, since it willl use (expensive) oil.
Since you bought the car used I doubt if the last owner put $7/quart oil in; he may have put in a lightweight dino oil, such as 5W20.
There is no problem in switching to synthetic (5W30 recommended) but any engine wear or leaks will make it an expensive proposition! Car manufacturers want every last fraction of a mile per gallon to escape CAFE penalties from the EPA. Their interest is not you, but their bottom line.
Most posters would recommend you use the oil that makes the engine last the longest, and that would be a 5w30 synthetic, such as Mobil !. But, depending on the mileage this may not work out for you if the engine is half worn. Your best alternative then is a regular 5W30 grade.
If your mileage has recently dropped, I doubt if your oil change had anything to do with it. There are just too many factors that can affect mpg. It is not reasonable to attribute any change in mpg to the oil you used. And a 5% drop (19 mpg vs. 20 mpg) is really too small to claim your car is behaving any differently than before.
Agree; car magazines use almost laboratory precision in measuring gas mileage when they test a vehicle. They will then also give the overall average for a standard set of tests, so it can be compared to other vehicles tested.
I have a new car, properly broken in at 6000 miles. The mileage lately has varied from 30 to 38 mpg because of weather, stop & go vs highway, speed, etc.
It is even difficult to duplicate your driving pattern fron one tank to the next.
There’s an acronym: RTFM. It means Read The F****** Manual. Seriously, the owner’s manual for your car will tell you the correct type of oil to use. Use what the manual says. Nothing else.