MPG increase with Synthetic?

[Stewart Fan]

On average will a car or truck get better gas mileage with synthetic oil?

 

[pscholte]

Compared to a dino of equal or greater viscosity, in most cases, yes; however (here's the hook), with some exceptions, the increase is so small that it only has value when its impact is measured over an extended period of time. Over a year's time, for example you WILL save money in reduced gasoline requirement (other factors being equal). I believe the real value in synthetics comes in the form of improved flow (especially in cold weather), better high temperature performance, increased engine cleaniness, and reduced wear.

 

[MRC01]

quote:

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Originally posted by pscholte:
I believe the real value in synthetics comes in the form of improved flow (especially in cold weather), better high temperature performance, increased engine cleaniness, and reduced wear.

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Plus one more: savings in $$$ and time from extended drain intervals.

 

[Jelly]

quote:

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Originally posted by pscholte:
Compared to a dino of equal or greater viscosity, in most cases, yes; however (here's the hook), with some exceptions, the increase is so small that it only has value when its impact is measured over an extended period of time. Over a year's time, for example you WILL save money in reduced gasoline requirement (other factors being equal). I believe the real value in synthetics comes in the form of improved flow (especially in cold weather), better high temperature performance, increased engine cleaniness, and reduced wear.

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...I agree with Pscholte.

When comparing a passenger-car SL mineral oil and an SL group IV or V synthetic oil of identical viscosity, the synthetic will indeed have improved flow in cold conditions, better high temperature performance, and, increased engine cleaniness, as well as the possiblity for reduced wear numbers.

 

[Forkman]

quote:

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Originally posted by Stewart Fan:
On average will a car or truck get better gas mileage with synthetic oil?

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I can't say that "every" vehicle will, but my fiancee's Regal with the 3800 V6 certainly did.

After having it for a year running on 10w30 Valvoline dino, we switched to M1 10w30 and have run that ever since.

We keep fuel/mileage logs in both of our vehicles and always fill up at the same station at the same pump to help reduce other variables such as the angle the car is setting at etc.

Her car was getting about 20 in town and 28 on the highway with the dino. With the M1 it was getting about 23 in town and 31 on the highway.
Averaging an entire year out with both the M1 and dino (in a spreadsheet) resulted in a cumulative average of 22MPG with the dino and 24MPG with the synth.

Is this realistic for most cars. Probably not. Could something else be causing it. Certainly, although I don't know what that would be since neither the brand of gasoline or typical driving conditions changed between the two years.