Regular vs. Premium Unleaded Gasoline.

[KrisZ]

I tried premium in my Mazda 3 several times and never noticed any difference in gas mileage, power, smoothness or any other aspect. But then again, why would I? My car is very well maintained, it never knocked or experienced pre ignition, old spark plugs looked great and my exhaust pipe has no soot on it what so ever.

Perhaps in cases where higher octane fuel makes a noticeable difference it is simply because not everything is 100%.

 

[Hokiefyd]

Originally Posted By: KrisZ
I tried premium in my Mazda 3 several times and never noticed any difference in gas mileage, power, smoothness or any other aspect. But then again, why would I?


One reason you might is if there is enough adjustment latitude in your car's engine management computer that enables it to advance spark and/or cam timing further than what is optimum for 87 octane.

Our old 2011 Camry, for example, seemed to gain 10-20 horsepower on 93 octane. I mean, it was a REAL difference. So much so that I used it all the time, simply because of the better throttle response. Mileage was up, too, which made the cost difference about a wash. Toyota obviously recommends 87 octane in this car, but that doesn't mean that it can't benefit from a higher octane...it simply indicates they're recommending the lowest octane generally sold to enable folks to use that grade of gas.

On the flip side, our 2008 Honda CR-V is more like your Mazda; I've ran numerous tanks of 93 octane through it and I can't tell a lick of difference in it. So I don't use it. There's apparently not as much of a range of adjustability in our CR-V's computer as there was in our Camry's computer.

Just as most cars that recommend 93 octane can adjust to run on 87, some cars that recommend 87 seem to be able to adjust to take advantage of 93.

 

[rjundi]

My MDX requires premium. If you skimp you get 1-2MPG less automatically.

The only time I noticed a power loss though was doing a 900' vertical climb over 1 miles distance on gravel roads to our family vacation house. Typically I can blast up at 35MPH+ with ability to floor it and accelerate as fast as I want. With regular I was flooring it and only could go 28MPH at best.

 

[exranger06]

My opinion: If your vehicle requires premium, use premium. Using a lower octane will probably reduce power and/or mileage at best, and may damage the engine at worst.

If your vehicle only requires regular, but says additional performace may be gained with premium, then run a few tankfuls of each, do the math, and use whichever you prefer.

If your vehicle requires regular and makes no mention of additional peformance with premium, or has no way of taking advantage of the higher octane, then use regular. Using higher octane is a waste of money in this case. All of my vehicles fall into this category, and I use regular.

 

[OVERKILL]

Originally Posted By: exranger06
My opinion: If your vehicle requires premium, use premium. Using a lower octane will probably reduce power and/or mileage at best, and may damage the engine at worst.

If your vehicle only requires regular, but says additional performace may be gained with premium, then run a few tankfuls of each, do the math, and use whichever you prefer.

If your vehicle requires regular and makes no mention of additional peformance with premium, or has no way of taking advantage of the higher octane, then use regular. Using higher octane is a waste of money in this case. All of my vehicles fall into this category, and I use regular.


Great summation

 

[stchman]

Originally Posted By: Peted
Originally Posted By: stchman
I had a discussion with someone the other day and we got on the topic of 87 vs. 93 octane gas.

He said that he uses premium in all his cars as the engine will last longer. What a bunch of [censored].

I told that if the manual does not state to use premium, then its use is at best a waste of money.

He said that his cars "feel" better when they run premium. Sounds like the placebo effect has kicked in.

A few months ago I tried running a couple of tanks of 93 in my Silverado and guess what, no change in mileage or power feel. All I did was waste ~$7 a tank.

He did not want to believe me that octane is just a combustion inhibitor. Oh well.


Sad to say, but You're in the wrong. I have your twin truck and 93 definitely makes a difference. Smoother idle, slightly better mpg .5-1, over all a slightly better sounding/running engine, a small difference but a difference none the less. You most likely can't notice small fluctuations in the engine. Some are able to, some are not. Or because you are so set on your bias, it inhibits you to notice any difference at all..


I am going to assume your Sierra has the 5.3L engine, the 6.2L engine requires 91 octane.

The ability to "feel" what you're speaking of is called the placebo effect. Smoother idle, better sound,

After running 2 tanks of 93 in my Silverado, the gas mileage was approximately the same on 87. Even if you get the phantom 0.5MPG, the MPG gain is not worth the extra cost.

Bias?!! There are MANY studies that show if your vehicle does not require premium, running premium is a waste of money. If you wish to run premium in your truck that does not require it, go right ahead, your choice.

 

[SteveSRT8]

^^^Right on the money. We have a ton of 5.3's here and they simply don't magically run better on high test.

I can't tell you how many folks have told me that their car 'runs better' on high test. And it may, but it is highly unlikely to be an improvement that is quantifiable.

If you really believe, then it's true... for you.

Some engines have the latitude in their programming and the ability to notice the increase. Some don't. Many here apparently think all mfgr's use the exact same tuning strategies. They do not...

 

[jimbrewer]

Originally Posted By: stchman
I still maintain that if the manufacturer recommends 87 octane, going to 93 will net you no benefit.


Maybe, but read that owner's manual carefully. Some of the manufacturers waffle on that quite a bit nowadays. Ford F-150 says to use premium while towing. Says elsewhere that the car "benefits" from higher octane gas. In yet a third place, it says to use 87 octane gas. You know the next line about about how its OK to use lower octane gas in high altitude areas? Ford doesn't put that in there anymore.

I'd go so far as to say that yeah, for marketing reasons they make sure they run on regular. But the cars really want Premium.

 

[stchman]

Originally Posted By: jimbrewer
Originally Posted By: stchman
I still maintain that if the manufacturer recommends 87 octane, going to 93 will net you no benefit.


Maybe, but read that owner's manual carefully. Some of the manufacturers waffle on that quite a bit nowadays. Ford F-150 says to use premium while towing. Says elsewhere that the car "benefits" from higher octane gas. In yet a third place, it says to use 87 octane gas. You know the next line about about how its OK to use lower octane gas in high altitude areas? Ford doesn't put that in there anymore.

I'd go so far as to say that yeah, for marketing reasons they make sure they run on regular. But the cars really want Premium.


GM does not waffle here with the Silverado.

4.3L, 4.8L, 5.3L
Quote:

For all vehicles except those with the 6.2L V8 engine (VIN Code 2),use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less
than 87, an audible knocking noise, commonly referred to as spark knock, might be heard when driving. If this occurs, use a gasoline rated at 87 octane or higher as soon as
possible. If heavy knocking is heard when using gasoline rated at 87 octane or higher, the engine needs service.


6.2L
Quote:

If the vehicle has the 6.2L V8 engine (VIN Code 2), use premium unleaded gasoline with a posted octane rating of 91 or higher. You can also use regular unleaded gasoline rated at 87 octane or higher, but the vehicle's acceleration could be slightly reduced, and a
slight audible knocking noise, commonly referred to as spark knock, might be heard. If the octane is less than 87, you might notice a heavy knocking noise when you drive. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, you could damage the engine. If heavy knocking is heard when using gasoline rated at 87 octane or higher, the engine needs service.


All this sounds to me if you own a Silverado not equipped with a 6.2L engine, use 87 or better octane. If you own a Silverado with a 6.2L engine, you can use 87 octane, but the engine may knock, so you really should use 91 octane or higher.

 

[asand1]

Peted
A calorie is a measure of energy that can be applied to any fuel, be it food, gasoline, or horse dung. You do not have the ability to feel a 5hpmeasure difference. It is only a percieved (in your head) difference.
Premium has less btu, calories, energy, etc lower the flash point to lessen spark knock.

 

[Shannow]

Premium doesn't necessarily have less BTUs, and flash point has nothing to do with spark knock.

 

[y_p_w]

Originally Posted By: asand1
Peted
A calorie is a measure of energy that can be applied to any fuel, be it food, gasoline, or horse dung. You do not have the ability to feel a 5hpmeasure difference. It is only a percieved (in your head) difference.
Premium has less btu, calories, energy, etc lower the flash point to lessen spark knock.

Not necessarily true. All of this is heavily dependent on the particular mixture of hydrocarbons.

 

[hattaresguy]

Originally Posted By: Shannow
Originally Posted By: hattaresguy
The gas companies are good at marketing, I still don't understand why their is a price difference other than because they can charge more.


then you don't understand oil refining...


Its not a business I'm involved in so no.

 

[Scott_Tucker]

Check out this for a look at the difference in btu in different gasoline.. Yes, it is racing fuel but it give the general idea.

http://www.ercracingfuels.com/sxs1.htm

 

[badtlc]

Originally Posted By: asand1
Peted
A calorie is a measure of energy that can be applied to any fuel, be it food, gasoline, or horse dung. You do not have the ability to feel a 5hpmeasure difference. It is only a percieved (in your head) difference.
Premium has less btu, calories, energy, etc lower the flash point to lessen spark knock.


91 and 87 octane have the same BTU content.

 

[y_p_w]

Originally Posted By: hattaresguy
The gas companies are good at marketing, I still don't understand why their is a price difference other than because they can charge more.

There's really nothing that makes distilled higher octane fuel much more or less expensive than lower octane fuel. They're just separated in the distillation process into "blendstock" streams. However, the difference in price is a matter of supply and demand. If they charged the same price, then who would buy regular? Everything about pricing and distribution is designed to get the oil refiner to use up nearly 100% of their output without having to store excessive amounts of fuel that they can't get off their hands. A refiner could make more premium by sending most of the high octane fuel output to making high octane fuel. However, they've got lots of fuel that once blended with oxygenates still isn't going to meet the 87 octane requirement for most cars. So some of the high octane fuel has to be blended to bring up the lower octane fuel to make it acceptable.

P. 27 is pretty good at showing the distribution of gasoline blendstocks produced in the refining process. It shows that the bulk of the gasoline output is reformate (92.5 AKI) and FCC naptha (86 AKI). Then there's other blendstock that's well under the requirements for regular, so they have to blend these with higher octane fuel to get it up.

http://www.theicct.org/sites/default/files/publications/ICCT05_Refining_Tutorial_FINAL_R1.pdf

This one is also pretty descriptive:

http://www.api.org/events-and-training/proceedings/proceedings/~/media/Files/Events/Conference%20Proceedings/Refining101forCustoms-March2012v6.ashx

No refiner is in the business of storing fuel long-term. It goes bad over time and you get complaints from your customers.

Now unleaded race fuel is very different.

 

[badtlc]

I have never understood why we don't just design everything to run on 91+ octane and get rid of the sub-par grades of gas. it would simplify production, distribution, pricing and even engine design while improving MPGs and emissions.

Maybe the market feels people must have choices to be happy.

 

[y_p_w]

Originally Posted By: badtlc
I have never understood why we don't just design everything to run on 91+ octane and get rid of the sub-par grades of gas. it would simplify production, distribution, pricing and even engine design while improving MPGs and emissions.

Maybe the market feels people must have choices to be happy.

Not practical. If that was done, what do you do with the fuel that can't be sold because it doesn't meet that requirement? The current system self regulates the distribution of gasoline. If you blended all the gasoline from a refinery, it might have an (RON+MON)/2 octane of 88. Add oxygenates and it might increase a point. It's a math/supply/demand exercise, and the target is to avoid refinery output going unused.

 

[SteveSRT8]

Thanks to y_p_w for that very informative post.

Marketing is a funny thing, we are manipulated in more ways than most would ever imagine. One pump only would save so much money it ain't funny!

But it will never happen due to the way folks think, and that is unlikely to change...

 

[Shannow]

ypw makes some really good points, and it's not the gas companies screwing us, as he says...you need to shift stuff.

Silly analogy, but look at the different prices of different cuts of animal, offal etc. etc.

Lamb shanks I used to buy for 50c, then some classy places in Sydney started "rustic" cooking, slow cooked braised shanks...formerly poor man's food...now they are $4-5 each. More people will pay more for them.