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Don't waste your money with Premium gas!


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45 replies to this topic

#21 OFFLINE   obob

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Posted 24 June 2013 - 01:25 PM

I know an argument from years ago was that premium gas was 'premium' because it contained additives to reduce knocking, but those additives did not contain the same energy potential as regular gasoline, so therefore a gallon of premium gasoline contained less energy than a gallon of regular, hence lower mpgs for a vehicle that could run on regular.

"There is little difference in energy content of regular versus premium gasoline. They both contain about 111,400 British Thermal Units of energy per gallon"

 

from http://www.consumere...vs_premium.html









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#22 OFFLINE   theblackcmax

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Posted 24 June 2013 - 01:53 PM

My father is friends with someone who owned a company who delivered gas to stations. And he said that some stations that are independently owned by certain people are a NO NO when it comes to premium gas. They will tell the drivers to dump regular gas into the premium storage tanks. He always said no and stopped delivering to them, but you don't know if everyone does that. Just be careful and try to go to stations which are corporate owned.



#23 OFFLINE   fotomoto

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Posted 24 June 2013 - 04:11 PM

The C-Max has very high compression compared to similar cars.  The high CR allows more power and better economy if the ignition timing is optimal.

Since the timing is computer controlled, I think it would be.  The CR listed in the owners manual, page 345, is 12.3 to 1.

 

My former Volt required premium yet it only had a 10.5 CR much less than the CMax.  Numerous Volt owners including myself noted an instant decrease in mpg when using regular unleaded.  It was just habit for me to punch the unleaded button at the pump instead of premium.   GM has taking a beating in numerous reviews and forums about this requirement so (putting my conspiracy theory tin-hat on) I think maybe Ford decided not to specify or recommend premium fuel since a 12.3 CR should deem such.  

 

I scanned this thread quickly but I don't think I saw anyone say they tried premium in the CMax and not get better results.  


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#24 OFFLINE   SnowStorm

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Posted 24 June 2013 - 06:00 PM

The C-Max has very high compression compared to similar cars.  The high CR allows more power and better economy if the ignition timing is optimal.

Since the timing is computer controlled, I think it would be.  The CR listed in the owners manual, page 345, is 12.3 to 1.

The C-Max has an Atkinson cycle engine where, quoting Wikipedia, "The effective compression ratio is reduced".  The 12.3 value is most likely the expansion ratio (actual change in cylinder volume).  We can't compare the 12.3 ratio Atkinson cycle to the same ratio Otto cycle.

 

For me, I'm not convinced either way yet but am leaning toward the possibility that higher octane could give better mileage.  From a marketing standpoint Ford would hardly dare to specify premium even if it gave better mileage.  It just wouldn't fly in the hybrid buyer market.  I've used E0 87 so far and may try 93 at some point but it will be a difficult comparison to make - too many variables. 


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#25 OFFLINE   fotomoto

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Posted 24 June 2013 - 06:12 PM

The C-Max has an Atkinson cycle engine where, quoting Wikipedia, "The effective compression ratio is reduced".  The 12.3 value is most likely the expansion ratio (actual change in cylinder volume).  We can't compare the 12.3 ratio Atkinson cycle to the same ratio Otto cycle.

 

For me, I'm not convinced either way yet but am leaning toward the possibility that higher octane could give better mileage.  From a marketing standpoint Ford would hardly dare to specify premium even if it gave better mileage.  It just wouldn't fly in the hybrid buyer market.  I've used E0 87 so far and may try 93 at some point but it will be a difficult comparison to make - too many variables. 

 

Very good points snow.  I forgot the Volt ICE is otto cycle and enthusiasts are expecting an atkinson ICE in volt 2.0

 

This time of year is great for me to compare tank to tank as day to day temps can vary only a degree or two (hot is hot) but unfortunately with our kids out of school my driving routine is not.



#26 ONLINE   Plus 3 Golfer

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Posted 24 June 2013 - 09:09 PM

Compression ratios have been increasing in modern engines while still using regular fuel. There's been significant engineering into the combustion process including piston and cylinder design, multiple injections per cycle, higher injection pressures and so forth such that gas engines can now run at higher compression ratios on regular gas.  Bottom line: CR alone does not dictate the use of premium fuel.

 

I also serious doubt that if premium fuel would yield 6% better FE (% price spread between 91 and 87 octane fuel), Ford would recommend regular. Ford would be talking EPA of 50/50/50 on premium. ;).


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#27 OFFLINE   salsaguy

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Posted 24 June 2013 - 11:26 PM

the top tier gas site refers to 24 gas companies, not just 76 so not sure how that is biased.

76 doesn't own them all.

 

Click on the "History of Top Tier" link to the right, you'll see that behind the top tier website is the gas company 76.  They are hawking how their gas has more additives that will remove those nasty deposits and will show you where to find a 76 station near you.  You can even watch a video and see what a supermodel thinks! (I'm not kidding!)

 

Just my personal opinion, I wouldn't trust anything she or they say.



#28 OFFLINE   salsaguy

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Posted 24 June 2013 - 11:37 PM

of course one could argue you could just buy regular 87 gas and add a bottle of Techron gas additive for about the same $5 or less and end up with the same test since Techron is the stuff they use in Chevron (top tier rated) gasoline.

 

Edit 6/25: corrected gas company. was Exxon. Is Chevron

 

 

 

I run premium (93 octane) for the additives, not octane. Since it costs me an extra $5 a tank for premium, that's about $20 more a month on fuel. I also use synthetic oil since I am going 10k on an oil change.


Edited by salsaguy, 26 June 2013 - 01:52 AM.


#29 OFFLINE   HPRifleman

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Posted 25 June 2013 - 08:18 AM

The Toptiergas domain name is owned by General Motors.

#30 OFFLINE   PapaJ

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Posted 25 June 2013 - 10:21 AM

The C-Max has very high compression compared to similar cars.  The high CR allows more power and better economy if the ignition timing is optimal.

Since the timing is computer controlled, I think it would be.  The CR listed in the owners manual, page 345, is 12.3 to 1.

 

Pointless to buy a car like a C-Max specifically engineered to burn regular and needlessly waste $.20 - $.30 per gallon buying premium fuel. The idea that you will get more power and/or better mileage using premium -- unless your manual specifices premium -- is an urban myth.

 

I do think there may be some benefit to Top Tier gas in terms of keeping your engine internals clean.

It is pointless to buy a car specifically engineered

 

The C-Max has very high compression compared to similar cars.  The high CR allows more power and better economy if the ignition timing is optimal.

Since the timing is computer controlled, I think it would be.  The CR listed in the owners manual, page 345, is 12.3 to 1.

 

to burn regular, then needlessly waste $.20 - $.30 per gallon buying premium fuel. The idea that you will get more power and/or better mileage using premimum -- unless your manual specifices premium -- is one of those urban myths that just won't die.

 

I do think there may be some benefit to Top Tier gas in terms of keeping your engine clean.In most cases, using a higher-octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner." - See more at: http://blog.truecar....h.fPxWmWOc.dpuf
In most cases, using a higher-octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner." - See more at: http://blog.truecar....h.fPxWmWOc.dpuf
In most cases, using a higher-octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner." - See more at: http://blog.truecar....h.fPxWmWOc.dpuf


#31 OFFLINE   SnitGTS

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Posted 25 June 2013 - 10:01 PM

the top tier gas site refers to 24 gas companies, not just 76 so not sure how that is biased.

76 doesn't own them all.

 

I didn't say 76 owned all the top tier gas stations, I said they owned that website that he was referencing.  If you go to the website and clicked on the 'history of top tier' link to the right it brought you to the 76 website.  On that website they are saying how their gas is better than anyone else's, where to find a 76 station, and a video to 'ask a supermodel her opinion'.  

 

I was saying that I wouldn't trust anything on that website because it is owned 76, in a way they are hijacking the top tier brand.

 

Edit:  If you click on the link from this forum, click on the 'home' tab at the top to see the 'history of top tier' on the right.


Edited by SnitGTS, 25 June 2013 - 10:04 PM.


#32 OFFLINE   Jus-A-CMax

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Posted 25 June 2013 - 11:00 PM

You know I might tank up the next one with regular and see what MPGs I get. My route is pretty much down pat, got great stats and I pretty much have the route keyed into my foot pedal. Who's gonna pay for the tank at Costco...should be there this Thursday ;)



#33 OFFLINE   zhackwyatt

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Posted 26 June 2013 - 09:17 PM

I didn't say 76 owned all the top tier gas stations, I said they owned that website that he was referencing.  If you go to the website and clicked on the 'history of top tier' link to the right it brought you to the 76 website.  On that website they are saying how their gas is better than anyone else's, where to find a 76 station, and a video to 'ask a supermodel her opinion'.  

 

I was saying that I wouldn't trust anything on that website because it is owned 76, in a way they are hijacking the top tier brand.

 

Edit:  If you click on the link from this forum, click on the 'home' tab at the top to see the 'history of top tier' on the right.

 

The Toptiergas domain name is owned by General Motors.

 HPRifleman is right, General Motors owns the toptiergas.com website (using whois lookup).  Probably some intern found a link with a description of Top Tier on the 76 website and that's why it's there.  I do not believe it's owned by 76.



#34 OFFLINE   Noah Harbinger

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Posted 02 July 2013 - 02:19 AM

You know I might tank up the next one with regular and see what MPGs I get. My route is pretty much down pat, got great stats and I pretty much have the route keyed into my foot pedal. Who's gonna pay for the tank at Costco...should be there this Thursday ;)

 

What you need to do is have someone ELSE do it: Flip a coin; heads = premium, tails = regular. Write it down - but they can't tell you! Then after the tank has been used up, try to guess which it was. Do this 10 times or so. 


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#35 OFFLINE   BIG ROCCO

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Posted 11 July 2013 - 02:32 PM

What you need to do is have someone ELSE do it: Flip a coin; heads = premium, tails = regular. Write it down - but they can't tell you! Then after the tank has been used up, try to guess which it was. Do this 10 times or so. 

 

 

That's a good idea!



#36 OFFLINE   Edsel

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Posted 11 July 2013 - 02:46 PM

Anyone started/stopped using premium and noticed any results?



#37 OFFLINE   GaryM

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Posted 08 August 2013 - 08:14 AM

Ever since computers started controlling ignition timing, there has been a debate about octane and performance/economy/etc. Before the computer was there, you had to dial in the timing to not knock too bad on whatever fuel you used. Some older cars even had an "octane" knob on the distributor. I used a fully programmable ECU in my turbo conversion on a 1983 Toyota Celica. It was fairly radical for the time, with 9.0 compression and 13 psi of boost. Pumping a real 300+ hp out of 2.4 litres with just one cam and 8 valves. Ignition timing was CRITICAL. and it HAD to run 93 or better octane. Even going to the west coast 91 pinged it so hard I ruin the rings. And that was with backing the timing down and lowering the boost to 11 psi, it would not go lower without a different wastegate. It did have a knock sensor, and I dialed it in to retard timing up to 15 degrees if it kept "hearing" knock. When I tuned it on 93 octane, I dialed it in so the knock retard would just hit 2 degrees. This made it so you barely ever heard even a single ping, but the ECU heard it and dropped that timing within a rotation of the crank. I did a couple hundred hours of data logging to get it right, and it paid off big time. That beast of a car would run 0-60 in under 5 seconds, and it also got 28.5 MPG.

 

So, what does this have to do with the C-Max????

 

Back the, my programmable ECU was an 8 bit processor running at 2 Mhz, with my couple hundred hours of data logging to dial it in. Todays ECU's have 32 bit processors running in the Ghz range, many times more memory, and the factories spends THOUSANDS of hours dialing in the base maps and very elaborate learning routines that I could not have come close to back in the mid 90's. What does that mean? These ECU's are what make it possible to run 12:1 and higher compression ratios on regular gasoline. Even back in the 90's the factory computers were quite good, and would set an error code if the knock sensor did not show any knock. The base maps do run close to the limits, and not just at full throttle, in fact, the maximum timing advance is under part throttle light load. At higher loads, the timing backs off a lot. Every fuel has a certain burn rate. The ideal timing is when the burn creates the maximum cylinder pressure without detonating with the crank at the correct angle to turn that pressure into torque. Getting it right at light load is where highway fuel economy comes into play. Have the spark a few degrees late, and you lose torque, so you need to burn more fuel for a given amount of power. Even my 2004 Camry 4 banger would ping a tick once in a while at part throttle, going up an incline in 5th gear is one example. Pushing the throttle a bit more, it would stop immediately, because the map had to retard timing at the higher load. All modern ECU's walk a fine line to get the most out of the fuel. In most cases, part throttle efficiency can increase a bit with higher octane fuel, but there is a flip side. Rarely will the increase cover the cost difference. The additives can also reduce the energy a little nulling any economy increase from the greater possible timing advance. Some engines actually run better with a faster burn rate (long stroke and wankel come to mind). Atkinson cycle is a bit of an odd ball. I really do not know how it effects the true cylinder pressure. It obviously creates less compression pressure, but since it still does have the longer expansion, I am sure the timing is still very picky if not more so. I have never tuned one, so I do not know how the burn rate of the fuel will effect it.

 

I have only run regular so far in my C-Max and I have been getting very good mileage, with my last 2 tanks running very close to 46 MPG. If I do decide to try premium, I will have to run at least 2 full tanks through to make sure the learning routines in the ECU can correct for the change. Just going to a different brand took a good 120 miles before my mileage was back to "normal". When I filled up at 7-Eleven instead of my normal Chevron, my MPG went from nearly 47 at the end of the previous tank to 43 for the first 1/8 tank plus with the same driving. But now at the 1/2 tank mark of this same tank, my average is back up to 45.9 with close to 48 on my last few trips. It certainly takes the ECU a bit of time to optimize the fuel in the tank. Just one tank of premium will not tell you much. And switching up and back with never tell you anything.

 

Cheap gas that advertises higher amounts of detergent sure sounds like a bad thing to me. Detergent does not contain energy, it is displacing fuel for soap. I would much rather have clean gasoline and a little detergent to just keep the injectors and valves clean. Would you wash your clothes in mud by just using twice the laundry detergent? "Top Tier" gas vs "Premium" gas is a different discussion. High quality 87 octane is better than 94 octane crap. My fuel ups in the C-Max are so far apart, it is tough to try to test multiple fuels. I will try a few tanks of Shell as that was what my Camry ran best on. Chevron is just the most convenient on my way home and also has a $0.20 per gallon discount when I use my Von's club card. Shell has the same deal if I went to Ralph's, but I do not shop there enough. I have used Sam's club gas in my Camry with decent results, so I may try them as well. Arco was BAD, to the point I would not even try a second tank to let the car try to learn it. The car would surge an buck even while on cruise control on a flat highway. My MPG dropped far more than the cost savings. I only will use them if I can't find any other station and my distance to empty is ZERO.


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#38 OFFLINE   Arthur

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Posted 27 August 2013 - 11:51 AM

The C-Max manual calls for 87 Octane, I wonder if the higher octane will cause any problems.. I use 87, and an additive for cleaning the top end from Amsoil every 5 tanks. PI performance improver 



#39 OFFLINE   Edsel

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Posted 27 August 2013 - 01:00 PM

I filled up with regular gas this time and have noticed no difference in 3/4 of a tank.  It's back to 87 octane for me. No more of this. :spend:



#40 OFFLINE   MacGyver

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Posted 21 October 2013 - 02:57 PM

Wow Gary, awesomely geeky! :drop: There should be a Wayne's World style emoticon; :not worthy: 








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