Anyone use Premium Fuel?

[James K]

This is a bit higher up on the page:



This jibes with the owner's manual, which says any performance increase will be most noticeable on hot days with the engine under heavy load.



The manual clearly states the engine operates on 87 octane, and it RECOMMENDS 91 octane if you need the most engine performance. If you aren't towing or hauling heavy load.



This is the PRIMARY benefit for EcoBoost owners. Ford's advertised horsepower specs are based on use of premium fuel. If you don't use premium your engine will knock at lower power demand--especially in hot weather--prompting the PCM to cut power output. How much? One owner in the Mustang EcoBoost community did before & after dyno runs with his stock 2.3L EcoBoost Mustang. With premium his engine achieved with a percent or two of advertised max power (310 HP). After switching to regular max power output dropped some 10%.



A couple of points on this comment: First, there have been a lot of different comparison tests on this subject over the years. IIRC, the test you refer to noted the 2-3% increase when the engine is operated near maximum power output. That's not a real-world test. Car & Driver did a comparison with four different cars under real-world driving conditions with mixed results. Keep in mind: for the mileage testing C&D drove each car over a specified course followed by a refill. It generally take the PCM several miles to readjust to a different octane fuel, and it's nearly impossible to refill a car to exact same level twice, so take that portion of the test with a grain of salt.



Seems logical, but you're missing some important factors. For one thing, detonation requires heat, which means high power demand. Below 50% maximum power there is almost nothing you can do with timing or mixture to induce detonation, because there simply isn't enough heat. At high power demand you are stuffing high quantities of air/fuel in the cylinder with the turbocharger, and the cylinder retains heat between combustion events. When the sparkplug fires, pressure in the cylinder goes way up, generating even more heat. With enough heat and pressure you get secondary, spontaneous ignition of the mixture in different areas of the cylinder. These generate there own flame fronts, separate from that generated by the spark event. Knock is the sound made by two (or more) flame fronts colliding.

Further, there is the issue of mixture. One of the ways designers keep detonation under control with a turbocharged engine is to enrichen the fuel/air mixture (i.e. add more fuel). A richer mixture burns more slowly, so it has the net effect of changing the timing at the cost of fuel efficiency. When you switch to premium fuel you can keep the mixture leaner at higher power output, thus efficiency improves.

These factors are why the owner's manual says you will see the most benefit from premium on hot days when the engine is under heavy load. It's only under those condition you'll experience detonation. At typical highway cruising speeds your engine is producing something less than 40 hp, and nowhere near the heat necessary to generate detonation. At that power output the PCM doesn't need to change mixture or timing when you switch between premium and regular.



I suggest you try again, but don't use the dash indicator, and hand-measure over several tanks. I've keep a running log of fuel use for my EcoBoost-equipped Bronco Sport since new. I've run both regular and premium several different times under different environmental conditions. For comparison, I run each type of fuel for at least three tanks, and hand measure. This is the best way to cancel out all the variables that factor in to fuel economy. You can read through the thread here. The bottom line for my driving conditions is there is no efficiency gain with premium fuel.

TL;DR: The owner's manual is your best source for operating instructions. If you need maximum power, or you just like to know that maximum power is always available, use premium. For normal operation save your money and use regular.

I knew I was opening a can of worms. I stated my case from what I believe to be an accurate understanding of the topic. I truly appreciate the differing takes on the subject. I really appreciate that everyone was civil and rational. At the end of the day the OP will just have to flip a coin.

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[zeen]

I'm certain this is all about the EPA mileage test. As has been stated numerous times, there is a slight increase in mpg, but not enough to justify the extra cost of premium. But for the EPA test, every tiny bit helps. So they are walking a fine line of recommending premium, so it's legal for the test, but saying it's safe (wink, wink) to run regular.

 

[Shakesbear]

With regular gas available around me for about $2.60/gal ($2.50/gal with my Circle K/Valero discount card), I'll be sticking with regular for the time being

 

[Mark S.]

I'm certain this is all about the EPA mileage test. As has been stated numerous times, there is a slight increase in mpg, but not enough to justify the extra cost of premium. But for the EPA test, every tiny bit helps. So they are walking a fine line of recommending premium, so it's legal for the test, but saying it's safe (wink, wink) to run regular.

EPA testing is done with regular unless the manufacturer requires the use of premium. EPA tested the Maverick using regular.

Correction: Apparently the EPA uses a standardized fuel called Indolene. According to this article at Motor Trend, Ford says its EcoBoost engines lose 3% on fuel economy while burning regular only on the most severe portion of the EPA-regulated cycle (i.e. high power), which makes up only 20% of the overall EPA test cycle. This matches up with the manual, which says you will see the highest performance gains under high power demand situations.

 

[sprubs]

Do I use premium fuel? No, I do not.

 

[RichardCranium]

Motortrend also wrote another article about Octane and made the point that I have made on several other posts, " Keep in mind, your engine needs to be designed, built, and calibrated for higher-performing fuels in order to realize any sort of gains." Most non turbo cars today are not calibrated for high octane fuels, so the computer sets defaults to where it should run properly on the lower octane fuel. The computer does not try to adjust for higher octane fuels, it just adjusts if it senses issues. That being said, high mileage engines may see more performance increases by running higher octane fuels. As cylinders wear, they create hot points that will lead to increased preignition possibilities. I had an old, worn out mitsubishi mightymax with a carburetor. It developed a ping, I adjusted the timing, but the ping eventually came back. If I put in high octane fuel, it went away.
Now, as others stated, Motortrend also mentions that for engines designed and calibrated for 87 octane, "Fuel with an 87 octane rating burns more quickly while higher-octane fuels burn more slowly. In engines designed for standard unleaded fuel, efficiency and performance is optimized for 87 octane and could actually perform worse with higher-octane fuel since the burn rate is slower."
Typically you have the NA/Atkins Cycle engines that are not high performance that run well, or even better on regular 87 octane, and the turbo, AKA high performance engines, that run better on higher octane but still run well on lower octane because of how they are calibrated.
It was mentioned earlier that some atkins cycle engines, specifically the prius, actually have issues with higher octane fuels because they are calibrated to run on the 87 octane.
Since this is in the hybrid subforum, we need to assume that OP has a hybrid and is asking other hybrid owners of their experiences, however, it appears that most responding to the thread that have noticed an increase in power are referring to their EcoBoost Mavericks.
My assumption would be that because the manual recommends higher octane under certain situations that Ford has calibrated the hybrid engine to run with 87 octane fuel, but can take advantage of the higher octane fuel only under certain situations in which a larger amount of power is needed. I may be incorrect, but I don't think most drivers drive with their gas pedal mashed to the floor all the time or towing 3200 lb trailers everywhere they go, and therefore will not notice the possible up to 10% power increase by running the higher fuel. Since the computer monitors and adjusts the ignition continuously, based on many factors, beyond acceleration and heavy towing, there probably is very little, or not noticeable changes in efficiency.
In conclusion, as stated before by many, the engine will not suffer from running 87 octane fuel because the system is calibrated to run on it. Running higher octane has the potential of creating more power under certain situations which most people do not take advantage of in daily driving.
Finally, it is really up to you to decide which fuel is the best for you. Whether it be performance, Environmentally friendly, or pocketbook friendly. Just remember, the placebo affect is a true phenomenon. As many people have stated, the computers in these trucks have memory and the settings adjust based on driving habits and conditions. That being said, if you put in premium gas, there will not be an immediate/dramatic change. Unless you completely drain your fuel system, it takes a few tanks before the fuel in your system truly gets up to the full octane rating of the pump. I haven't seen anyone mention it, but if you are running 87 octane fuel and put 3/4 of a tank of 91 octane, the fuel in your tank is not 91 octane. Those of us that have the option of mid grade 89 octane fuel, it is just a mixture of the 87 and 91 octanes. Gas stations only have 2 tanks, one for 87 and one for 91. The fuel is mixed at the pump. Therefore, those that fill up with 91 and then immediately feel the power as they accelerate from the gas station are just feeling that effect. So I recommend, as others have, try it for a few tanks before you make your decision. My guess is that on your 3rd tank of 87, you will not notice enough of a difference to make it worth the higher price of premium.
Motortrend Article

 

[TheSEARCH]

This is a bit higher up on the page:



This jibes with the owner's manual, which says any performance increase will be most noticeable on hot days with the engine under heavy load.



The manual clearly states the engine operates on 87 octane, and it RECOMMENDS 91 octane if you need the most engine performance. If you aren't towing or hauling heavy load you may use 87 octane without reservation.



This is the PRIMARY benefit for EcoBoost owners. Ford's advertised horsepower specs are based on use of premium fuel. If you don't use premium your engine will knock at lower power demand--especially in hot weather--prompting the PCM to cut power output. How much? One owner in the Mustang EcoBoost community did before & after dyno runs with his stock 2.3L EcoBoost Mustang. With premium his engine achieved within a percent or two of advertised max power (310 HP). After switching to regular max power output dropped some 10%.



A couple of points on this comment: First, there have been a lot of different comparison tests on this subject over the years. IIRC, the test you refer to noted the 2-3% increase when the engine is operated near maximum power output. That's not a real-world test. Car & Driver did a comparison with four different cars under real-world driving conditions with mixed results. Keep in mind: for the mileage testing C&D drove each car over a specified course followed by a refill. It generally take the PCM several miles to readjust to a different octane fuel, and it's nearly impossible to refill a car to exact same level twice, so take that portion of the test with a grain of salt.



Seems logical, but you're missing some important factors. For one thing, detonation requires heat, which means high power demand. Below 50% maximum power there is almost nothing you can do with timing or mixture to induce detonation, because there simply isn't enough heat. At high power demand you are stuffing high quantities of air/fuel in the cylinder with the turbocharger. The more fuel/air you burn, the more heat. And the cylinder retains heat between combustion events. When the sparkplug fires, pressure in the cylinder goes way up, generating even more heat. With enough heat and pressure you get secondary, spontaneous ignition of the mixture in different areas of the cylinder. These generate their own flame fronts, separate from that generated by the spark event. Knock is the sound made by two (or more) flame fronts colliding.

Further, there is the issue of mixture. One of the ways designers keep detonation under control with a turbocharged engine is to enrichen the fuel/air mixture (i.e. add more fuel). A richer mixture burns more slowly, so it has the net effect of changing the timing at the cost of fuel efficiency. When you switch to premium fuel you can keep the mixture leaner at higher power output, thus efficiency improves.

These factors are why the owner's manual says you will see the most benefit from premium on hot days when the engine is under heavy load. It's only under those condition you'll experience detonation. At typical highway cruising speeds your engine is producing something less than 40 hp, and nowhere near the heat necessary to generate detonation. At that power output the PCM doesn't need to change mixture or timing when you switch between premium and regular.



I suggest you try again, but don't use the dash indicator, and hand-measure over several tanks. I've keep a running log of fuel use for my EcoBoost-equipped Bronco Sport since new. I've run both regular and premium several different times under different environmental conditions. For comparison, I run each type of fuel for at least three tanks, and hand measure. This is the best way to cancel out all the variables that factor in to fuel economy. You can read through the thread here. The bottom line for my driving conditions is there is no efficiency gain with premium fuel.

TL;DR: The owner's manual is your best source for operating instructions. If you need maximum power, or you just like to know that maximum power is always available, use premium. For normal operation save your money and use regular.

That was quite the reply to a really silly subject. If your driving around with it floored all the time then you have other problems not related to the car. Will it extend the life of the engine NO. Is it cost effective NO. Will you get the most power with high test Yes. If your running from Alien space craft I suggest you always use high test. Or if it makes you FEEL better do it too.

 

[Raymundo76]

I knew I was opening a can of worms. I stated my case from what I believe to be an accurate understanding of the topic. I truly appreciate the differing takes on the subject. I really appreciate that everyone was civil and rational. At the end of the day the OP will just have to flip a coin.

Right on. Each of us appreciates almost all posts on this topic and will use the discussion as a guide to choose the octane that we think to be appropriate. After time, with use and further information, we reserve the right to change our minds if need be.

 

[Tim d]

Hey all,
Was reading through the manual and it says:

"Your vehicle operates on regular unleaded gasoline with a minimum pump (R+M)/2 octane rating of 87.
Some fuel stations, particularly those in high altitude areas, offer fuels posted as regular unleaded gasoline with an octane rating below 87. The use of these fuels could result in engine damage that will not be covered by the vehicle Warranty.
For best overall vehicle and engine performance, premium fuel with an octane rating of 91 or higher is recommended. The performance gained by using premium fuel is most noticeable in hot weather as well as other conditions, for example when towing a trailer."

Any first hand experiences on MPG with 91+ vs 87? Would it be worth the cost in the long run?

I tried premium in my ecoboost once, couldn't see any difference. Possibly towing a heavy load might see a difference?

 

[flashfearless]

Hey all,
Was reading through the manual and it says:

"Your vehicle operates on regular unleaded gasoline with a minimum pump (R+M)/2 octane rating of 87.
Some fuel stations, particularly those in high altitude areas, offer fuels posted as regular unleaded gasoline with an octane rating below 87. The use of these fuels could result in engine damage that will not be covered by the vehicle Warranty.
For best overall vehicle and engine performance, premium fuel with an octane rating of 91 or higher is recommended. The performance gained by using premium fuel is most noticeable in hot weather as well as other conditions, for example when towing a trailer."

Any first hand experiences on MPG with 91+ vs 87? Would it be worth the cost in the long run?

Nope. No need.

 

[MarcoG]

Hey all,
Was reading through the manual and it says:

"Your vehicle operates on regular unleaded gasoline with a minimum pump (R+M)/2 octane rating of 87.
Some fuel stations, particularly those in high altitude areas, offer fuels posted as regular unleaded gasoline with an octane rating below 87. The use of these fuels could result in engine damage that will not be covered by the vehicle Warranty.
For best overall vehicle and engine performance, premium fuel with an octane rating of 91 or higher is recommended. The performance gained by using premium fuel is most noticeable in hot weather as well as other conditions, for example when towing a trailer."

Any first hand experiences on MPG with 91+ vs 87? Would it be worth the cost in the long run?

Complete waste of hood money. Picked up my hybrid in Florida, drove cross country in November from Key West back to Los Angeles. Even in 8000 feet in Sante Fe, NM and through high desert in Las Vegas, engine perfect on streets at 25mph and Highway at 80-85 mph on 87 octane...Bunk.

 

[MarcoG]

Complete waste of hood money. Picked up my hybrid in Florida, drove cross country in November from Key West back to Los Angeles. Even in 8000 feet in Sante Fe, NM and through high desert in Las Vegas, engine perfect on streets at 25mph and Highway at 80-85 mph on 87 octane...Bunk.

Mind you that wasn't in heat, nor do l tow. My thoughts on that say try it, you hear a knock, top off with premium during periods of more engine stress.

 

[Slimshady]

In hot weather an engine has a higher tendency to knock or ping. Only if you are knocking pinging is 91 going to help. Otherwise a lesser grade is just fine. All grades contain the same energy content, so mileage is the same, regardless.

not necessarily...the engine has knock sensors that adjust the ignition timing to stop the knock....so in reality....the higher octanes will give you the amount of torque and HP that Ford advertises....maybe more if Ford rates it on 87 octane.

 

[Slimshady]

Complete waste of hood money. Picked up my hybrid in Florida, drove cross country in November from Key West back to Los Angeles. Even in 8000 feet in Sante Fe, NM and through high desert in Las Vegas, engine perfect on streets at 25mph and Highway at 80-85 mph on 87 octane...Bunk.

cant really compare the hybrid vs ecoboost...since its gutless and has very little HP

 

[Slimshady]

my bad guys...i didnt realize this was a hybrid subforum...you guys run all that 87....and leave the 91-93 octane for us ecoboosters....my BAD.

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