My source From this link: http://www.mobiloil.com/USA-English/...l_1_0W-20.aspx

Mobil 1 0W-20 Advanced Fuel Economy

Mobil 1 0W-20 Advanced Fuel Economy is engineered to deliver outstanding engine protection and to offer improved fuel economy in vehicles where SAE 0W-20 or 5W-20 oil is recommended. This low friction, fully synthetic formula increases engine efficiency and offers the best fuel economy in the Mobil 1 line. Over the life of your vehicle, Mobil 1 Advanced Fuel Economy can save over $400 in fuel costs.

 

What is the price of that oil compared to the regular Mobil 1 synthetics? I did the calculator on their website, and it showed I would only go 10 miles farther on a tank of gas, and only save $24 a year. (I drive about 20,000 miles a year, and gas has been about $2 a gallon here in the Chicagoland area.) That little difference makes me think there could be a number of factors that could attribute to the gain in fuel economy more than the actual oil used.

 

I have always used Mobil-1 Synth since the get go, and stay fairly constant at 35mpg.
I find that mileage is more impacted with outside temps than with any oil. I use synth for the superior lubrication qualities and duration between changes like many others have echoed here.
In colder climates (in phx az) I drop to around 32-33mpg.

 

Have you considered any sources other than the advertisement from the company that makes the oil? Exactly what does Fully Synthetic mean to the consumer?
What standards is a company required to meet to put those words on the bottle and who sets those standards?

 

Oil related question?

Do any of the FEH engines have a windage tray or an oilscraper?

I know the oil has the viscosity of water these days, but windage should still improve mileage (horsepower too).

MM

 

I have not opened up a FEH engine but the manual does not show a windage tray. I doubt a windage tray would do much good as they really are only useful at high rpm with thicker oil.

 

Well, thanks for all of the info--I feel a little like the shortstop that causes the bench clearing brawl....but this community is very cool.

 

I use Mobil One. On my 92 Suburban 5.7L engine at 371,000 miles I get 17 mpg and 5-6,000 miles per quart. I put in M1 at 7741. On my 01 Mustang Cobra 4.6l DOHC at 250,000 miles I get 27 mpg at interstate speeds (75 out here) with about 6000 miles per quart. I put in M1 at 8 miles (yes eight!).

I changed my FEH to Mobil One at 78 miles. Currently at 42473. The extra-ordinary fuel mileages you will see here are not typically repeatable for the long term. Despite seeing mileages as high as 37 mpg, my long term average is 30.7. I calculate this by spreadsheet and tracking the fuel and odometer reading on each fill-up.

I believe in M1 but the increase in mileage is the smaller of the benefits. It is slicker with reduced friction which ought to show in reduced mileages.

What I see as the major benefit is reduced wear and tear inside the engine coupled with reduced starting load on the starting system in very cold weather. This oil flows at lower temperatures than other oils and so eases the cold weather starts.

If you plan on keeping a car for the long term, as I do, then this oil would be worth it just for the reduced wear & tear, as you can see in my other two cars above.

Read the labels & Material Safety Data Sheets: Not all synthetics are 100% synthetic despite their labels. In my research few are truly 100% synthetic. If the MSDS mentions waxes and such, then it is a dino oil base with a synthetic additive package. The benefit of reduced friction comes from the sum characteristics of the oil not from an additive package to a non-synthetic base stock.