Semi-Syn oil = mpg increase

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Car: 1992, Pontiac Grand Am, 3300cc, auto, mileage 170k.
Driving environment = Houston traffic, Hot, wet, & sticky. ~48 gallons of gas used. ~1100 miles driven
I changed oil about a month ago from ordinary oil to a semi-synthetic blend. I don't remember what kind. Cost about $2.50 quart vs. $0.95 for regular oil. My gas mileage has gone from avg 21.8 mpg to 23.8 mpg. I have run 4 tanks of gas through my car so far. The increase was noticed for each tank. Nothing else in my driving, car, or environment has changed therefore the 2 mpg better mileage is probably from the semi-syn oil. Power seems to be about the same. Engine temp the same, etc.
Based on the old mpg I would have used 50 gallons of gas instead of 48 gallons. The semi oil increases my driving expense by ~$1 per month if I change oil at 4k miles.
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Gee, to bad you don't remember what kind you used. Because it's definitely a magic blend.
Brian
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Why? It sounds reasonable to me. I may go back to the ordinary oil next time to see if my mileage drops.
el Diablo wrote:

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I've been using synthetic oil for 8 years and have never seen an increase in mileage on any of my vehicles. But that's not why I use it.
So if this is reasonable to you what facts do you base your test of reasonable results from? I mean besides your saying that for 4 tanks of gas you are getting better mileage?
Synthetic oil manufactures claim less engine wear and a higher engine protection level. They don't claim you'll get better mileage.
Brian
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el Diablo wrote:

Well, you could go back to regular oil for two oil changes and see if your vehicles get worse mileage.
My facts are: 21.8 mpg before oil change 23.8 mpg after oil change Everything else is about the same. I cannot come up with any other reason for the increase.
If you can suggest another cause for the better mpg, I will definitely check it out and let everyone know the results. I've gone through everything I can think of.
I doubt if I will use syn or semi-syn oil again. It's not worth the expense. It will be interesting to see if my mileage drops.
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Well, you could go back to regular oil for two oil changes and see if your vehicles get worse mileage.
My facts are: 21.8 mpg before oil change 23.8 mpg after oil change Everything else is about the same. I cannot come up with any other reason for the increase.
If you can suggest another cause for the better mpg, I will definitely check it out and let everyone know the results. I've gone through everything I can think of.
I doubt if I will use syn or semi-syn oil again. It's not worth the expense. It will be interesting to see if my mileage drops.
replay..... Sure it paid for it's self if what you say is true.
1100 miles driven getting 21.8 mpg would be 50.4 gallons of gas used. 1100 miles driven getting 23.8 mpg would be 46.2 gallons of gas used.
Savings of 4.2 gallons of fuel at $1.75 per gallon would be a savings of $7.35
5 qts. of standard oil at $0.95 per quart = $4.75 5 qts. of semi synthetic oil at $2.50 per quart = $12.50 A difference of $7.75 So it cost you $0.40 to use the semi synthetic oil. If you change the oils at 3000 miles ( that leaves 1900 miles on your oil change not accounted for) you will make $12.75 after you break even from the additional cost in oil.
Any more financial advise I must charge for.
Brian
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el Diablo wrote:

Hmmm... Good point. Looks like I need to re-do my math.
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I can come up with a reason. Different times: different weather patterns, different luck hitting stop and go lights, different (fill in the blank of one of hundreds of little variables that can make at least a little difference here). Heck I mean weather alone can change humidity content, temperature, barometric pressure and on and on. All of which can affect combustion efficiency and rain and such can certainly affect tire drag etc.
Long and short of it is that even 4 tanks is not a good enough sample size. If you continue to see this, say after 10 tanks, and then switch back to normal oil for 10 tanks and see a drop, then you might be onto something. The thing is, if synthetic improved MPG you would think that would be touted as a feature by those who make and sell it.
Also, did you make ANY other changes to your vehicle along with the switch in oils? A change in performance could be attributable to something like that too.
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SgtSilicon wrote:

I changed the RF hub about the same time as the oil. I just thought of a possibly major item: school got out about that same time, too. Not as many cars on the road. School should start up again right about the time to change oil again. Ambient temp went from 93F to 97F about that time, also.
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Less cars on the road definitely could be a factor. Uuuhg, don't ya just hate getting stuck behind those school buses?
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Which brand of synthetic oil is delivering absolutely zero fuel economy increase? I am sorry to hear this. :-(

SAE fuel economy test results demonstrate AMSOIL synthetic lubricants improve fuel economy. With my own vehicle, I noted a 15.5% fuel economy increase chaning from dead dinosaur lube to AMSOIL synthetic motor oil.
All the Best, Steve 15 year independent AMSOIL Synthetic Lubricants Dealer Offering wholesale prices to all Dealerships available E-mail me for details
To respond via e-mail, simply take the, "REMOVEXX" out of my return e-mail address.
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Little Stevie. Ahh your back. I though Googelplex had chased you off of usenet. Want to post your K&N bullshit again? Charles
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What K&N bullshit was that?
On Mon, 05 Jul 2004 06:01:52 GMT, "Charles Bendig"

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wrote:

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Wet filters around MASSIVE quantities of dust/dirt. Of course not! GW
Charles Bendig wrote:

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Paul wrote:

Hi..
Is it possible that you changed viscosity from a very heavy oil to a 0-20 or something?
Ken
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A drop from a 30 weight to a 20 weight might do something. I don't see that the 0 would make any difference except if doing a lot of warm ups in very cold weather.
On that subject I would like for someone to explain why not use 0W30 in warm weather. The only good reason I can come up with is if you are using conventional oils you will have more viscosity improvers (VI) in it than you would in 5W30 or 10W30 - something to avoid. Since most synthetics do not use VI I see no reason not to use 0W30 all year (other than that 0W30 usually costs more).
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HRL wrote:

Hi...
I can't speak for the experts; but I've never seen an SAE 0 to anything in conventional oils or even synthetic blends... and I suspect if they were available I would have... I live in an area where minus 40 degrees isn't very uncommon.
SAE 0 is available in pure synthetics, but is very expensive...
Then again, the oil folks suggest that it need be changed less often, so... dunno.
Take care.
Ken
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Yeah, I think you are right. I bought some 0W30 Mobil 1 for a special price when it first came out. I have used Mobil 1 since it was first brought out and came only in 5W20. I put it in my big block 450 and it performed better than ever before with absolutely no oil usage. I was rather amazed because it was using quite a bit of 10W40 when pulling heavy loads over mountain passes. Later I became convinced that the engine was getting so hot it was vaporizing the conventional oil.
What I was really asking was about what I often read in owners manual. They may say to use 0W30 only if the temperatures are below some given point. I really don't see why that should be a limitations. All W30 oils are supposed to be the same viscosity at 100C (212F). In addition all those oils have thicker viscosity's when they are cold. Even 0W oil at 0C has a thicker viscosity than W10 when it is hot.
So why is it specified for cold weather only. My only thought is that the person that prepared the specification didn't even think about it. I have lived in those -40 degree areas. I would have no hesitation of using 0W30 all year. - Just trying to find a lubrication expert to help me out.
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Ken Weitzel wrote:

Good thought... The old oil was mostly 10w30 with a little 10w40 added in. I usually use what ever is cheapest at Wal-Mart or O'Reilly's.
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