Better Fuel Economy Suggestion for All Cars

Messages
1,462
Location
CA
Originally Posted by Wolf359
Wow, that's a really big spread between regular and premium. The mid grade is a real money maker though, should be half of regular and half of premium so it should be $3.25 instead of $3.70. So they make an extra 45 cents per gallon.
The 91 does not say "Contains 10% Ethanol" either. Costcos in CA have a 20c to 30c spread between 87 & 91 so about 5%.
 
Messages
108
Location
Flyoverland, KY
In my experience, using the car computer to monitor avg fuel economy while driving the same section of interstate on cruise control on multiple trips, the biggest variable in the "observed" fuel economy is simply wind direction. My mileage using the same car, same tank of gas, same tire inflation, will vary 10% from minimum to maximum depending on which way the wind is blowing. In extreme conditions, like a stiff headwind from a cold front coming through, I have seen the spread widen to as much as 15%.
 
Messages
4,030
Location
WA
First off..congrats on the Navigator OP, nice ride 👍 Not sure I would consider a 1mpg difference statistically significant, certainly not worth the added cost of premium IMO. Unless you have a dirty combustion chamber or it's called for in the owners manual, you're [censored] your money away using a higher octane fuel. But..it's your wallet, your car...do as one does.... *and you're not likely to see any meaningful difference in mpgs from using a 0w20 v. a 5w20 v. a 5w30. At operating temp there's just not that much difference in viscosity (drag) to make a difference IRL applications. Maybe in a lab on a Dyno but certainly not out on the streets.
 
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Messages
640
Location
Colorado
Originally Posted by AEHaas
I chose to put in 5-20 Mortorcraft oil at the 3,000 mile mark. I was hoping to maybe get a little better fuel economy. No change.
20 weights won't always get better fuel economy in an engine speced for a 30 weight. (The 4:00 minute point of Angela's presentation at https://www.youtube.com/watch?v=0B6SHa4qv60 ) I would suggest using a thin-side 5w30 with great specs, as in Pennzoil Platinum 5w30 which should give you optimal results (kv100 9.8, add some fuel dilution, only a little, and it's a heavy-side 5w20).
Originally Posted by CharlieBauer
Originally Posted by Wolf359
Wow, that's a really big spread between regular and premium. The mid grade is a real money maker though, should be half of regular and half of premium so it should be $3.25 instead of $3.70. So they make an extra 45 cents per gallon.
The 91 does not say "Contains 10% Ethanol" either. Costcos in CA have a 20c to 30c spread between 87 & 91 so about 5%.
Yet ethanol or methanol can increase octane rating. You did NOT want to be chased by an ME 109 with methanol-water injection activated, as one example from 1944. You only need it injected at the right times: "Cohn and Bromberg dealt with that problem using alcohol. When the SI engine is working hard and knock would otherwise occur, a small amount of ethanol or methanol is injected into the hot combustion chamber, where it quickly vaporizes, cooling the fuel and air and making spontaneous combustion much less likely. In addition, because of alcohol's chemical composition, its inherent knock resistance is higher than that of gasoline. The alcohol can be stored in a small, separate fuel tank — as exhaust-cleanup fluid is stored in a diesel engine vehicle. Alternatively, it could be provided by onboard separation of alcohol from gasoline in the regular fuel tank. (Almost all gasoline sold in the United States is now a mix of 90 percent gasoline and 10 percent ethanol.)" -- http://news.mit.edu/2018/mit-researchers-gas-alcohol-engine-getting-world-off-dirty-diesels-0613
 
Messages
1,005
Location
Alberta
Why you would go to a lighter than spec'd oil on a direct injection twin turbo vehicle making 125 hp/litre and even more than that in torque makes me shake my head. Ford tried 5w20 when the first generation of that engine came out and ditched it for 5w30. You buy a navigator then scrimp on fuel by trying thinner oil? It'll run fine on regular fuel, and the way you describe your driving, you'll never need the extra few ponies premium brings. Save your bucks there.
 
Messages
272
Location
California
I also notice slightly better MPG with higher octane fuels. But more importantly, I find my vehicles run like crap on cheap octane 87. They stumble and bog. No issues with 89 or 91.
 
Messages
8,761
Location
North Carolina
I filled up the Touareg with diesel and got 29.2mpg! Running premium in the Atlas does not affect the fuel economy at all - but it does smooth out the engine.
 
Messages
1,976
Location
FL
Best fuel economy vehicle you can buy! Run it with gas - any gas - diesel, or just used motor oil from your fellow BITOG'ers! Save the planet's resources and save some money while you're at it! [Linked Image from i.ytimg.com]
 
Messages
8,051
Location
Michigan
Originally Posted by Jimmy_Russells
OEM's have actually been pushing for 91 to become regular fuel for quite some time. They believe they can really increase both mileage and power if that was the case. I'm all for it if they can leave the "regular" prices as they are now and just eliminate 87 and 89 altogether. Maybe have 91 as regular and 93 or 94 as premium.
I remember GM made a proposal on that a while back. It all sounded good until I read to the lower part of the story, where they said the octane increase would come from a higher percentage of ethanol. NO SALE, said I, unless the high-ethanol 91 could be made to cost the same as 89, and give me the same driving range on a tank of fuel. This I doubt could be done.
 
Messages
2,410
Location
South Carolina
I tried higher octane in my 4Runner but not the spread you did. My OM says 87 or higher so I tried 89. I ran several tank fulls so the computer could adjust (timing, etc). No change in MPG. Guess I don't have enough compression in the old girl to take advantage of the slower burning fuel.
 
Messages
8,051
Location
Michigan
Originally Posted by OVERKILL
Originally Posted by PimTac
My experience has shown better fuel economy with running 91-92 octane premium. The difference is about 1.5 to 2 mpg. This is on a Mazda SkyActiv 2.5 naturally aspirated engine which has 13:1 compression. In addition, response and power, especially going up hills is better with the premium. It might cost me more but with everything I've observed I will stay the course.
Yes, typically engines with higher compression will benefit. Our 5.7L "requires" 87 at minimum, but recommends 89. Since Costco only carries 87 and 91, it gets 91. The CR on it is 10.5:1.
Have you tried a 50/50 blend of the 87 and 91 at the pump to get a lower-cost 89? I do that sometimes on my Camaro when I pull into a station that has 87 and 93. Sometimes I can actually get 87/93 blend, which may or may not be 90 at lower cost than I can get 89 from the pump.
 
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27,876
Location
PNW
Originally Posted by Rmay635703
This is sort of like saving money on a hybrid or EV, TCO is terrible because you pay thousands more up front then hundreds extra of taxes every year which wrecks any savings potential [Linked Image]
That a crazy huge price difference between octanes. Most I've ever seen here is maybe 20-25 cents difference between octanes. Who would use 87 mid grade or 91 high octane when the 89 is well over a dollar per gallon cheaper.
 
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17,602
Location
...
Originally Posted by A_Harman
Originally Posted by OVERKILL
Originally Posted by PimTac
My experience has shown better fuel economy with running 91-92 octane premium. The difference is about 1.5 to 2 mpg. This is on a Mazda SkyActiv 2.5 naturally aspirated engine which has 13:1 compression. In addition, response and power, especially going up hills is better with the premium. It might cost me more but with everything I've observed I will stay the course.
Yes, typically engines with higher compression will benefit. Our 5.7L "requires" 87 at minimum, but recommends 89. Since Costco only carries 87 and 91, it gets 91. The CR on it is 10.5:1.
Have you tried a 50/50 blend of the 87 and 91 at the pump to get a lower-cost 89? I do that sometimes on my Camaro when I pull into a station that has 87 and 93. Sometimes I can actually get 87/93 blend, which may or may not be 90 at lower cost than I can get 89 from the pump.
I haven't considered that. Fortunately the price spread here seems to better better than what others are posting.
 
Messages
1,397
Location
PEARL River la
On my Caravan it is a flex fuel vehicle so I tried 89 octane and took awhile to adjust before it got smooth but still not perfect and maybe 1 mpg change not enough for me to use regularly. On regular it is smooth through out RPM range and all sites and manual states tuned for regular. Timing only changes with ethanol level so I run regular.
 
Messages
783
Location
Austin Texas
I have a slightly different take on this:: perspective: I own and drive a 2017 GLS 450 and I use primarily mid-grade gasoline. Mercedes wants me to use premium gasoline. On several long (2000+ mile) road trips, I have achieved almost 30 MPG over an entire day:: [Linked Image] This being almost 8 MPG better than EPA simply shows how much knowing how to drive influences how many miles per gallon one gets.

GLS45003.JPG
 
Messages
11,469
Location
Florida, Cape Coral
I think the "one octane" fuel for all new vehicles would be 93 or 94. That would basic eliminate the 87 and 89 for all except maybe for stationary use. That would simplify things for the gasoline producers ane we would have higher standard compression daily. drivers give better fuel economy. There wouldn't be the 30% increase that we pay now for premium over 87 octane that some naysayers suggest. I believe it could be a win-win for all. Ed
 
Messages
337
Location
Lake County, Ohio
Originally Posted by tcp71
Why you would go to a lighter than spec'd oil on a direct injection twin turbo vehicle making 125 hp/litre and even more than that in torque makes me shake my head. Ford tried 5w20 when the first generation of that engine came out and ditched it for 5w30. You buy a navigator then scrimp on fuel by trying thinner oil? It'll run fine on regular fuel, and the way you describe your driving, you'll never need the extra few ponies premium brings. Save your bucks there.
I have read the same thing, the EcoBoost engines should run the 5W30 oil. I don't know what repercussions you would have running a 0W20 or 5W20 while under factory warranty if engine work was required. Stick with the factory recommendation regarding the oil until the warranty is up in my opinion.
 

OVERKILL

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Messages
46,201
Location
Ontario, Canada
Originally Posted by A_Harman
Originally Posted by OVERKILL
Originally Posted by PimTac
My experience has shown better fuel economy with running 91-92 octane premium. The difference is about 1.5 to 2 mpg. This is on a Mazda SkyActiv 2.5 naturally aspirated engine which has 13:1 compression. In addition, response and power, especially going up hills is better with the premium. It might cost me more but with everything I've observed I will stay the course.
Yes, typically engines with higher compression will benefit. Our 5.7L "requires" 87 at minimum, but recommends 89. Since Costco only carries 87 and 91, it gets 91. The CR on it is 10.5:1.
Have you tried a 50/50 blend of the 87 and 91 at the pump to get a lower-cost 89? I do that sometimes on my Camaro when I pull into a station that has 87 and 93. Sometimes I can actually get 87/93 blend, which may or may not be 90 at lower cost than I can get 89 from the pump.
No, but given how cheap 91 is at Costco (cheaper than 89 at most gas stations) I'm not too concerned about it. It's not worth the hassle to try and mix it myself at the pump, particularly given how busy Costco is.
 
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