Don't waste your money with Premium gas!

[plus 3 golfer]

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. ;).

[salsaguy]

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.

[salsaguy]

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 June 26, 2013 by salsaguy

[HPRifleman]

The Toptiergas domain name is owned by General Motors.

[PapaJ]

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.com/2011/03/03/premium-vs-regular-gas/#sthash.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.com/2011/03/03/premium-vs-regular-gas/#sthash.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.com/2011/03/03/premium-vs-regular-gas/#sthash.fPxWmWOc.dpuf

[SnitGTS]

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 June 26, 2013 by SnitGTS

[Jus-A-CMax]

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 ;)

[zhackwyatt]

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.

[Noah Harbinger]

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. 

[BIG ROCCO]

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!

[Edsel]

Anyone started/stopped using premium and noticed any results?

[GaryM]

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.

[Arthur]

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 

[Edsel]

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:

[MacGyver]

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

[fbov]

First off, Gary, I had a '73 Celica, and your reports of varying mileage with different gas brands would explain a recent trip we took... and it adds another control/noise factor!

 

The one other point is to remember we have Atkinson cycle engines, 12.3:1 compression assumes a 2L intake. at 1.8L, it's more like 11:1 compression, but with a 10% longer power stroke. Conversely, a hybrid engine runs at higher avg. load, so one would expect an adaptive engine to eventually use the added octane productively. It's something to test...

 

HAve fun,

Frank

[Tree63]

In my part of Canada, ethanol is added to Regular (up to 10% in 87 octane) but not to Premium (91).  I don't know if the octane level is maintained with the ethanol added, or if  it is 87 before adding the ethanol and it slips a bit.

 

With my last car (2007 Nissan Sentra), I tried Premium for 6 months and basically saw a 10% FE improvement with a 12-14% price premium.

 

Based on reading earlier postings on the Forum, I decided to try Premium for July-Dec, and am basically seeing the same results (a little behind with Fuelly entries).  (My 600+ tank reported in Forumm was on Regular.)  I'm up to 33000km/20000 miles so well past any break-in considerations.

 

Another factor:  Had the PCM update done about a week ago so too early to add that into the picture, but seemed a bit better on highway trip to the cottage, even with colder weather (mid 30's F) - 5.8 vs 6.2 l/100km at about 110km/hr.

 

Regardless the ride in C-Max is great.

 

ps - tried a tank of "super premium" (octane 94) from a national brand and FE dropped!!  Maybe ECU reprogramming couldn't handle it.

Edited October 26, 2013 by Tree63

[ptjones]

IMO from the Testing I've done Premium does improve MPG's around one or so, but not worth the money.(20-30 cents/gal). Pure gas(90 octane) improves about 2MPG still not worth it.(70-80 cents/gal.)

Paul

[Tdefny]

I don't buy into the whole idea of higher octane gas paying off in MPG. Octane rating measures the ability of a fuel to resist detonation (early ignition). Ethanol increases octane rating but decreases mileage, as it is less volatile than gasoline.

 

A higher compression engine needs the detonation resistance but can get better performance from the higher compression. It needs to detune itself slightly or risk damage if a lower grade of fuel is used. Our Atkinson-Miller cycle engine is more of a high expansion engine. It doesn't use the high compression to get more fuel into a tighter space like a performance engine. Rather, it uses a normal charge and retains it slightly longer to get a little more thermal efficiency.

 

The energy from fuel comes from breaking carbon bonds and turning them into CO2. Ethanol has fewer carbon bonds and thus less energy. I believe that Ethanol is all they have used to raise octane rating since MTBE was banned, but I am not sure of that.

[ptjones]

I don't buy into the whole idea of higher octane gas paying off in MPG. Octane rating measures the ability of a fuel to resist detonation (early ignition). Ethanol increases octane rating but decreases mileage, as it is less volatile than gasoline.

 

A higher compression engine needs the detonation resistance but can get better performance from the higher compression. It needs to detune itself slightly or risk damage if a lower grade of fuel is used. Our Atkinson-Miller cycle engine is more of a high expansion engine. It doesn't use the high compression to get more fuel into a tighter space like a performance engine. Rather, it uses a normal charge and retains it slightly longer to get a little more thermal efficiency.

 

The energy from fuel comes from breaking carbon bonds and turning them into CO2. Ethanol has fewer carbon bonds and thus less energy. I believe that Ethanol is all they have used to raise octane rating since MTBE was banned, but I am not sure of that.

They use lead in AVGAS and EPA continues to threaten to ban it,but with no viable replacement  they can't.(it's not a big problem % of volume is small) I'm only using my experience, but for what ever reason all FORD cars That I have owned have gotten better MPG's with Premium over Regular. And it's still not worth the additional cost unless you have need to go farther. Pure gas is the best, but very expensive here.

Paul

[marshtex2]

I spent 30 years in fuel research at big ol' Texaco, Product Research, and we looked long and hard into everything about the various grades of fuel.

 

The higher grades of gaso had more aromatics than Regular making them more dense, more mass per unit volume.  The carburetor cars showed better mpg with the higher grades because the carburetor system sucked the gaso over a hump to get it into the metering port.  About the same mass of the more dense fuel was sucked over and that meant less volume.  Hence fewer gallons to go the mile, throttle position staying constant.  That led to all kinds of myths about better mpg with Premium gaso and was great as a selling point for the more profitable product to buyers who didn't need the increased octane rating.  Back with leaded gaso, the lead increased the fuel density, and more lead was in the premium gaso to get the higher octane rating, hence contributing to the better mpg impression.  The volatility of the fuel influenced startablilty and drivability at lower temperatures.  The more volatile components are less dense and would tend to take away from an mpg rating.

 

With the expanded use of fuel injection, which meters the fuel by volume in a sealed system, fuel volatility was less to no influence and the direct effect on mpg went away.  However, the same volume of the more dense fuel means more mass of fuel into each combustion event, hence more power.  A driver looking for fuel economy and pussy footing the throttle pedal can get the desired performance/power with slightly less throttle thereby bringing a little better mpg. 

 

A second however is that most drivers' rampage on the throttle overrides these effects and any improved mpg won't be seen.  It takes very carefully controlled conditions to document these differences.

 

This consideration carries on to ethanol or any oxygenate.  They are less dense than the gasoline hydrocarbon and additionally bring in less energy for their combustion event.  Thus they are detrimental to fuel economy on a per gallon basis at equivalent power settings.

 

Marshall

Edited October 28, 2013 by marshtex2

[Swamp45755]

I have a 2018 CMax. I tried both regular and premium fuel. The manual states premium gas is preferred. And true to the manual I get better mileage and performance with premium fuel. The CMax sips fuel so unlike my Mercedes which averages 27 mpg, I am currently averaging 41.3 mpg with 1000 miles on the CMax. I suspect my mileage will improve when I clock more mileage on the CMax. I believe the engineers at Ford know what octane works best.

[Swamp45755]

I have a 2018 CMax. I tried both regular and premium fuel. The manual states premium gas is preferred. And true to the manual I get better mileage and performance with premium fuel. The CMax sips fuel so unlike my Mercedes which averages 27 mpg, I am currently averaging 41.3 mpg with 1000 miles on the CMax. I suspect my mileage will improve when I clock more mileage on the CMax. I believe the engineers at Ford know what octane works best.

[ptjones]

So do CMAX owners. :)  It may not be totally cost effective, but I like the extra range. :) Join fuelly.com  to keep track of your mileage. BTW Odometer is off by 1.6 to 2.2% so you can check with GPS , you will be getting better mpg's than you think.

 

Paul

Edited February 27, 2018 by ptjones

[MaxHeadroom]

2015 C-Max Owner's Manual states:  "Octane Recommendations:   We (Ford) recommend regular unleaded gasoline with a pump (R+M)/2 octane rating of 87. Some stations offer fuels posted as regular with an octane rating below 87, particularly in high altitude areas. We do not recommend fuels with an octane rating below 87. Premium fuel will provide improved performance and is recommended for severe duty usage such as trailer tow."

 

Assuming this is the same wording that Swamp45755 (see a couple of posts above) has in his 2018 C-Max (congrats on your purchase BTW) Owner's Manual, I interpret the statement as you only get an MPG benefit from premium fuel octane only if you drive hard, meaning the engine does sense potential knock and will retard the timing if necessary (when piezo knock sensors detect knock).

Thing is, it won't knock if you aren't driving hard and your engine then doesn't have to retard timing.

 

It is possible it will keep gradually advancing timing (for better MPG) until it senses knock, constantly "hunting" for that optimal timing adjustment as you drive.  Premium gas would allow more advance of timing, giving us slightly better MPG.    I'm not sure if timing advance is there, or if there is much of it, from the baseline engine map though.

Maybe I can figure out if I start seeing advance of timing using the FORScan (Ford-specific smartphone ELM327 OBDII) app.

It could be the Ford engineers actually run the engine on the baseline engine map, and only provide the freedom to retard engine timing (knock sensed), not potentially advance it gradually.  Anybody know if the engine control software algorithms actually do advance timing beyond the stored look-up table engine map value?

 

Biggest fuel problem is ethanol usage.  Ethanol is less energy dense than pure gasoline.  Our C-Max's, like most Fords, can use up to 15% ethanol fuels, E15.  (Can't use E85, the high-ethanol 85% extreme fuel out there.) 

Typical gasoline sold has about 10% ethanol (E10), so we lose about 3% or so MPG (-1.5 MPG) just from the energy density problem with those blends.

Pure gasoline is better for MPG, if you can find it !!