Shell V-Power test - Page 3 - Fuelly Forums

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Old 07-13-2007, 06:11 PM   #21
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Second segment complete; 33.43MPG over 325 miles. This tank included two trips in driving rain plus several less-than-optimum commutes, so I'm not surprised the figure is down a little.

But, I've been thinking...

Before this test, I was doing P&Gs with the transmission in neutral. Since I wasn't (and still am not) sure how safe that is for my automatic, I decided to try keeping it in "drive" for a while to see how closely I could approach the "N" numbers by feathering the accelerator during glides. I made that change about the time I did the first V-Power fill.

I thought I was getting nearly the same figures in "D", but that doesn't seem reasonable. So maybe not; perhaps the V-Power is contributing a little extra and canceling the loss?

Therefore, on this tank I'm going back to "NICE-ON" P&G to see what happens to the numbers.

Rick
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Old 07-13-2007, 07:28 PM   #22
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ehh its prolly so minescule that weather could be affdecting it... or any number of causes.
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Old 07-14-2007, 05:42 AM   #23
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Could be... but the only way to find out is to try.

Rick
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Old 07-19-2007, 05:03 AM   #24
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Third segment complete; 35.29MPG over 318 miles. Returned to NICE-ON P&G for this tank and, as I expected, FE jumped.

For comparison, the most recent prior tank driven that way was 33.64MPG, but the pump was labeled "up to 10% ethanol." The tank before was at 34.11MPG and was also NICE-ON P&G, but it included a lot of mountain and foothills driving.

So even though this tank is a new "personal best" (60% over EPA, go me! ), it's arguably in line based on the earlier numbers (especially if we assume my driving skills have continued to improve.)

Two more V-Power tanks to go, then I'll drop back to the cut-rate stuff.

Rick
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Old 07-25-2007, 05:30 AM   #25
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Fourth segment complete; 36.24MPG over 305 miles. At this point I have to cautiously admit V-Power (or Shell in general) might be helping, as there's been a definite upward trend over the last few tanks.

Know variables, in order of likelihood as regards better mileage:
  • I returned to NICE-ON P&G last tank.
  • My hypermiling skills continue to improve (I hope! )
  • The weather hasn't been as insanely hot over the last few tanks
  • Last two tanks have used GPSr mileage while my instrument cluster is being repaired
The last point is a total wild card, since I've never bothered to check odometer calibration. The VW's speedo is known to read a little high, but if that's reflected in the odometer the GPSr mileage readings would be lower if anything. My repaired cluster is expected back today or tomorrow, so I'll have an answer on this point fairly soon.

The fact that I stopped using P&G around the same time I started the V-Power test and kept about the same numbers -- and FE jumped when I started P&Ging again -- certainly implies I'm getting more miles per gallon on the Shell stuff. If that's indeed true, I can think of a few explanations. In what I think is decreasing order of probability:
  • The lower octanes are E10 but V-Power contains no ethanol
  • The "slippery stuff" Shell adds to their fuels reduces engine friction
  • V-Power really is usefully cleaning my engine
  • My engine is taking advantage of the higher octane
I read the bit about E10 in a discussion somewhere, but I haven't confirmed it yet. If it's true and the cause of better gas mileage, then dropping to mid-grade Shell should cause my numbers to drop. (But, does anyone add ethanol to their Summer blends, or is that just a Winter thing?)

"Slippery gas" is a Shell claim I recently heard. Supposedly they include additives to reduce friction. If this is the only factor, then dropping to regular Shell should keep my numbers up and returning to cut-rate gas should cause them to drop.

The engine-cleaning thing, if true, should result in my numbers staying up even after returning to el-cheapo gas.

If it's a knock-limiting issue, then one of mid-grade or regular Shell should drop my numbers, but they should go back up if I use anyone else's mid-grade or premium.

I'm currently on the fifth and what was supposed to be the final tank of Shell. But depending on how the numbers go I may stay with Shell a while longer to see if I can gather more information. It'd be nice for this to yield a hypothesis as to what effect V-Power (or Shell in general) had (if any), so others can run actual controlled experiments.

Rick
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Old 07-25-2007, 06:04 AM   #26
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Quote:
Originally Posted by Rick Rae View Post
I read the bit about E10 in a discussion somewhere, but I haven't confirmed it yet. If it's true and the cause of better gas mileage, then dropping to mid-grade Shell should cause my numbers to drop. (But, does anyone add ethanol to their Summer blends, or is that just a Winter thing?)
Depending where you are, there can definitely be ethanol in Summer blends.
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Old 07-25-2007, 07:36 AM   #27
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if it helps, I've found that different cars react to different fuels. For example, my old 96 Tahoe would return 2MPG better on Shell than on anything else. But, other vehicles would not. It could be your car just likes Shell gas as my Tahoe did. When you shift back to El Cheapo, if the improvement came from Shell's detergent then mileage should drop slowly back to what it was. If it is the car likes Shell, then mileage should drop back to what it was within a tank, no more than 2.

Also found that with the Tahoe, if I had to grab the occasional tank of crap, there was usually enough Shell fuel to keep the engine happy with the mix, and mileage would stay up, but on the next tank mileage would drop off.

And, did the math, every MPG better you get is worth about 12 cents at the pump when mileage is in the teens, so if one brand gets you 15 and another gets you 16, the gas with better mileage is the better choice even if it is more expensive, as it is cheaper per mile. To calculate cost per mile, divide the cost of fillup by miles travelled.
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Old 07-27-2007, 05:52 AM   #28
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When you shift back to El Cheapo, if the improvement came from Shell's detergent then mileage should drop slowly back to what it was.
Yes, very slowly indeed as gunk rebuilds, I'd think.

The original plan was to switch back to cut-rate gas after this fifth tank. But with the apparent Shell (or at least V-Power) -specific MPG improvement and the list of possibilities I posted the other day, I may modify that. I'll have to fill again next Wednesday or so, and I'm considering maybe staying with Shell but dropping to their mid-grade for a few tanks to see what happens, then their regular for a while, and then going to generic el-cheapo stuff.

I'm undecided at this point. If anyone sees a reason why I might get more useful information one way than the other, please chime in.

Rick

P.S. Thanks for the comments on cost-per-mile... definitely something to consider when choosing fuel. Hey Matt, how about a MP$ line on the gaslog charts?
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Old 07-27-2007, 07:32 AM   #29
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haha yep engines don't gunk up like that with ANY sort of regular maintenence, mainly oil changes and tune ups. stupid shell commercial.

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hahaha i laugh so dang hard at thier stupid comercial they have. about 2 identical cars running around one uses the allmighty v power while the other uses cheapo gas. then magically the shells is nice and clean while the other has what looks to be black corn flakes stuck to it...i have NEVER seen gunk that bad in an engine...its amost impossible... ive seen some funky carbon build up but no way was that comming off without a scraper....
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Old 07-27-2007, 01:22 PM   #30
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On mine, it was all 87 octane. Just can't bring myself to buy anything over 87 for a vehicle that doesn't require it. I did do some experimentation with the different Shell octanes in the Tahoe though, there was no difference in how it ran or fuel economy with the higher octane.
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