Re: Surprising increase in truck MPG

"Ed Huntress" <huntres23@[EMAIL PROTECTED]
> wrote in message 
news:4808bff1$0$11639$607ed4bc@[EMAIL PROTECTED]
>
> "Ignoramus15242" <ignoramus15242@[EMAIL PROTECTED]
> wrote in 
> message news:CJydne3zE43oIZXVnZ2dnUVZ_rKtnZ2d@[EMAIL PROTECTED]
>>I have a Chevy Silverado pickup that is by now about 18 months old.
>>
>> I was never able to get more that about 220 miles out of a 22 
>> gallon
>> tank of gas, sometimes even less.
>>
>> However, the last three refills, gave me 280, 266, and 283 miles 
>> per
>> refill. (I usually run until my tanks gets fully empty, since I 
>> have
>> an emergency gas canister for the instance when I run out of gas).
>>
>> This represents approximately 22% increase in MPG that I have hard
>> times explaining. I see three possible explanations.
>>
>> 1) Just before those refills, I did an oil change and used Mobil 1
>> synthetic oil. The previous oil changes were at a service station.
>>
>> 2) The engine had a chance to "burn in" and naturally improved its
>> efficiency
>>
>> 3) something is seriously mistaken in my measurements.
>>
>> I am at a loss and am very puzzled. Can synthetic oil really 
>> account
>> for that much of an increase? I highly doubt it.
>>
>> i
>
> Mobil itself claims only a 2% improvement in fuel economy, with 
> comparable oil weight. My experience is somewhat better, but, like 
> you, I can't really account for break-in and so on.

Mobil does not claim regular Mobil 1 provides a 2% increase. They do 
claim the new - "Mobil 1 0W-30 Advanced Fuel Economy is engineered to 
deliver outstanding engine protection and to offer improved fuel 
economy in vehicles where SAE 0W-30, 5W-30 or 10W-30 oil is 
recommended." They further claim  (for the new grade) - " potential 2% 
fuel economy improvement (based on a comparison versus those grades 
most commonly used). Actual savings are dependent upon vehicle/engine 
type, outside temperature, driving conditions, adjusting tire 
pressure, and your current engine oil viscosity."

I am confident that if you compared "regular" Mobil 1 0W20 to the 
Motorcraft Sysntehtic Blend 5W20 oil, you won't detect any significant 
mileage improvement (assuming a careful long term comparison). Fuel 
economy improvments are associated with two processes - reduced 
pumping losses and reduced friction. Pumping losses are primarily 
related to the oil viscosity. 5W20 oil, at least when new, has similar 
viscosity in most climates whether it is synthetic or conventional. Of 
course in very low temperature situation, synthetic oil might provide 
a benefit until the engine warms up, but this is trival for most 
people not in Canada or Alaska. Friction reduction is mostly 
accomplished through additives. One interesting fact is the that the 
test to determine if an oil qualifies for the Energy Conserving" 
designation compares the oil under test to a synthetic oil. To 
qualify, the oil under test (either syntehtic or converntional) must 
demonstrate a significant improvement in fuel economy comapred to the 
refernce synthetic oil.

> I use Mobil 1 5W-20 in my Ford Focus, and I intend to stick with it.

I use Mobil 1 in my Fusion and Frontier and plan to stick with it as 
well. I don't use it for the fuel savings.. I have compared the 
mileage for multiple vehicles when using Mobil 1 versus conventional 
oil (of the same viscosity) and never been able to detect a 
significant difference in fuel economy. I beleive Mobil 1 is better 
quality oil and that it provides superior protection to most 
conventional oils. Mostly I like the idea if I miss my regular oil 
change, I have some margin.

Ed