the deal on premium/mid grade gas

[elkhunter11]

Originally Posted by Deo101

It's been said but I"ll repeat Octane Rating=Resistance to detonation. So if you don't have a high compression ratio you're wasting your money. It is actually less explosive. I was sure the purple gave me more power in the old 67 352" Of course newer vehicles ecm's will compensate for this but all in all is a waste of cash.

The compression ratio is not the only factor as to whether detonation will occur, but since you mentioned compression ratio. what do you consider to be a high compression ratio? 10 to 1? , 11 to 1?, 11.5 to 1?

[Deep]

I totally agree with Roger- Synthetic oil, new air filter and ensure the tires are at max for good mileage.

[a little redneck]

If your manual says 87 then stick with regular fuel octane fuel. I run all my small 4 stroke and 2 stroke engines with premium (snowblower, chainsaw, mower etc) as well as 2 stroke snowmobiles. Some cars are required to run premium such as the gasoline engine Mercedes vehicles. If the fuel is to sit for a while, use premium fuel and add a stabilizer.

[pinelakeperch]

Originally Posted by elkhunter11

[B]The key phrase being" in many cases" ." Many" does not mean "all", so that means that in some cases, a higher octain fuel may increase performance or fuel mileage significantly. This is exactly why I mentioned testing fuels with different octane ratings in your vehicle.

As well the recommendations in most manuals state that the engine is designed to operate on gasoline with an octane rating of 87 octane or higher. or with gasoline with a minimum octane rating of 87. Nowhere does it state in my manuals that the vehicles run best with 87octane gasoline.

I can guarantee you that any increased gas mileage found with premium fuel wouldn't exceed the extra cost of the fuel. As I stated earlier, with current premium and regular prices, on a 60 litre tank of gas you would have to get more than 15 litres better gas mileage with premium just to break even.

Again, using the 20 cent difference found at Shell, Husky, Esso, etc, you're paying a $12 "premium" for premium gas per tank. $12 buys you 16 litres of regular fuel at $.75 per litre. I can guarantee you that switching to premium won't save you 16.1 litres of fuel. It wouldn't save you half of that. Or a quarter.


Actually there is a reason for doing so, they don't want people thinking that they will have to use high octane fuel to obtain the best performance, even if it is true. They know that some people would choose another vehicle, if they thought that the vehicle would not run at it's best with 87 octane gasoline.

I can guarantee you that any increased gas mileage found with premium fuel wouldn't exceed the extra cost of the fuel. As I stated earlier, with current premium and regular prices, on a 60 litre tank of gas you would have to get more than 15 litres better gas mileage with premium just to break even.

Again, using the 20 cent difference found at Shell, Husky, Esso, etc, you're paying a $12 "premium" for premium gas per tank. $12 buys you 16 litres of regular fuel at $.75 per litre. I can guarantee you that switching to premium won't save you 16.1 litres of fuel. It wouldn't save you half of that. Or a quarter.

Referring to manufacturer's incentive to not recommend premium fuel, if premium fuel in everyday engines has the possibility of reaping the benefits that you claim it does (increased performance, increased gas mileage), manufacturers would have incentive to design their engines to use it. Car ads revolve around gas mileage, and to a lesser extent, performance. Can't say I've ever seen a car ad that revolved around "this thing runs on regular gas"!

[elkhunter11]

Ah, but if premium fuel in everyday engines has the possibility of reaping the benefits that you claim it does (increased performance, increased gas mileage), manufacturers would have incentive to design their engines to use it. Car ads revolve around gas mileage, and to a lesser extent, performance. Can't say I've ever seen a car ad that revolved around "this thing runs on regular gas"!

I didn't say that it offers significantly superior performance in all applications, but I can tell you that it offers significantly superior performance and mileage in some applications. My motorcycle specifies 91 octane fuel, and when I use 94 octane fuel, the mileage does increase noticeably. For that reason, I use 94 octane fuel when it is available. Then again the engine management system on that engine is much more sophisticated than most are. However, it costs more to produce that engine management system, so many manufacturers stay with a simpler/cheaper system to keep the price point down.

But as you yourself posted earlier:

Plenty of independent tests have been done, and the verdict is that the extra cost in many cases isn't worth it if the manufacturer doesn't recommend it.

That "in many cases" was an admission that that isn't always the situation" in every case". You didn't even post "in almost every case", but instead chose the words "in many cases".

By the way, you messed up quoting me, as I didn't post everything that your previous post is apparently quoting me as have posted. You posted the statements below, even though your post makes it looks like you are quoting me.

Again, using the 20 cent difference found at Shell, Husky, Esso, etc, you're paying a $12 "premium" for premium gas per tank. $12 buys you 16 litres of regular fuel at $.75 per litre. I can guarantee you that switching to premium won't save you 16.1 litres of fuel. It wouldn't save you half of that. Or a quarter.

[pinelakeperch]

Originally Posted by elkhunter11

I didn't say that it offers significantly superior performance in all applications, but I can tell you that it offers significantly superior performance and mileage in some applications. My motorcycle specifies 91 octane fuel, and when I use 94 octane fuel, the mileage does increase noticeably. For that reason, I use 94 octane fuel when it is available. Then again the engine management system on that engine is much more sophisticated than most are. However, it costs more to produce that engine management system, so many manufacturers stay with a simpler/cheaper system to keep the price point down.

But as you yourself posted earlier:



That "in many cases" was an admission that that isn't always the situation" in every case". You didn't even post "in almost every case", but instead chose the words "in many cases".

By the way, you messed up quoting me, as I didn't post everything that your previous post is apparently quoting me as have posted. You posted the statements below, even though your post makes it looks like you are quoting me.

I did mess up quoting you, my apologies.

I am not sure why you are bringing up a motorcycle that already requires premium fuel when the discussion involves everyday vehicles that require 87 octane. I drive a tuned 5 cylinder turbo Volvo. I use premium fuel because my car is tuned for 91+ octane. Will it run on 87? Yes, but not optimally. I am happy to change my quote to "in virtually every case", as I am referring to everyday vehicles that require 87 octane from their manufacturers. And in "every single case" the difference in gas mileage between premium and regular will not not make sense economically. "Making sense economically" would be referring to gaining returns that are beyond breaking even. That is something that will not happen.

As far as performance gains on the cars I'm referring to, it isn't possible to quantify if the gains are "worth it". 20 cents extra per litre means something different to different people. Independent dyno runs have shown absolutely no gain in power. If someone notices a small improvement and feels that it's worth the extra 20 cents, have at it.

[Mugs29]

I will put my real world experience in here. The local gas station in northern Alberta ran out of regular so I put 3/4 of a tank of premium. I noticed that my truck had a bit more power because a hill coming home from work. It would make me downshift into 3rd 3/4 of the way up but for that week it would pull all the way up in 4th with power to spare. My truck is a silvarado with a 4.3 v6 (I know tiny engine.) I continued to alternate fuel ups between reg and premium and every time there was a difference in power. Checked out the owner manual and it said use higher octane at higher elevations when required. All of my small engine tools and toys get premium because they sit a while between use. Now that moved south to the flat land I would never put premium in my truck.

[elkhunter11]

Originally Posted by jhutter

I did mess up quoting you, my apologies.

I am not sure why you are bringing up a motorcycle that already requires premium fuel when the discussion involves everyday vehicles that require 87 octane. I drive a tuned 5 cylinder turbo Volvo. I use premium fuel because my car is tuned for 91+ octane. Will it run on 87? Yes, but not optimally. I am happy to change my quote to "in virtually every case", as I am referring to everyday vehicles that require 87 octane from their manufacturers. And in "every single case" the difference in gas mileage between premium and regular will not not make sense economically. "Making sense economically" would be referring to gaining returns that are beyond breaking even. That is something that will not happen.

As far as performance gains on the cars I'm referring to, it isn't possible to quantify if the gains are "worth it". 20 cents extra per litre means something different to different people. Independent dyno runs have shown absolutely no gain in power. If someone notices a small improvement and feels that it's worth the extra 20 cents, have at it.

The biggest difference between you and I, is that I am not making a blanket statement without actually testing for myself. You initially made a statement that had merit, because there is some data to support it, but since I pointed out that it doesn't fully support your argument, you change it to better support your argument. The only problem with your new statement, is that there are hundreds of models of vehicles/engines, and only a small percentage have been tested with fuels of various octanes to determine how that engine will react to the different octane levels.

And of course you have also overlooked the fact that some premium gasolines are advertised as containing no ethanol, while most if not all regular gasolines contain 10% ethanol. The fact that ethanol contains less energy, means that you have to burn more of it to get the same energy. That has been proven in many tests. So not only can you gain extra mileage if the computer compensates for the higher octane by advancing the timing, but you also gain mileage by burning an ethanol free fuel that contains more energy per volume. Of course I won't go making blanket statements about the results that a person could expect with every vehicle because only a small percentage of the vehicles on the market have been tested with gasolines of various octane ratings.

The bottom line is that in many cases( your first and correct phrase) burning a higher octane fuel than is specified by the manufacturer likely won't increase the fuel efficiency significantly if at all, because the engine management system is not capable of adapting to take advantage of the higher octane fuel. However some more sophisticated engine management systems are capable of advancing the timing to take advantage of the higher octane fuels, and they will produce better performance and fuel mileage as a result.

[pinelakeperch]

Originally Posted by elkhunter11

The biggest difference between you and I, is that I am not making a blanket statement without actually testing for myself. You initially made a statement that had merit, because there is some data to support it, but since I pointed out that it doesn't fully support your argument, you change it to better support your argument. The only problem with your new statement, is that there are hundreds of models of vehicles/engines, and only a small percentage have been tested with fuels of various octanes to determine how that engine will react to the different octane levels.

And of course you have also overlooked the fact that some premium gasolines are advertised as containing no ethanol, while most if not all regular gasolines contain 10% ethanol. The fact that ethanol contains less energy, means that you have to burn more of it to get the same energy. That has been proven in many tests. So not only can you gain extra mileage if the computer compensates for the higher octane by advancing the timing, but you also gain mileage by burning an ethanol free fuel that contains more energy per volume. Of course I won't go making blanket statements about the results that a person could expect with every vehicle because only a small percentage of the vehicles on the market have been tested with gasolines of various octane ratings.

The bottom line is that in many cases( your first and correct phrase) burning a higher octane fuel than is specified by the manufacturer likely won't increase the fuel efficiency significantly if at all, because the engine management system is not capable of adapting to take advantage of the higher octane fuel. However some more sophisticated engine management systems are capable of advancing the timing to take advantage of the higher octane fuels, and they will produce better performance and fuel mileage as a result.

You mean the engine management systems found in cars that recommend premium fuel?

My posts on this issue have been centred around whether the cost/benefit makes sense for regular vs premium fuel.

Let's break it down to a single question. Focusing solely on gas mileage, something that is quantifiable, do you believe it is plausible in a vehicle that doesn't require premium fuel to gain returns in terms of improved gas mileage while using premium fuel that are fractionally better than if using regular fuel, while accounting for the difference in cost?

There is no point arguing the performance aspect. While I believe that any perceived gains are due almost entirely to the placebo effect, there could very well be actual gains, albeit small ones.

[gulfman]

Originally Posted by Heyupduck

If I'm going over the mountains I put it in, now gas is cheap I might top off the tank with it to give my engine a treat (which is kinda stupid maybe because I have no evidence to go on other than the higher cost)

Thanks in advance

Forget about the car......treat your wife

[elkhunter11]

You mean the engine management systems found in cars that recommend premium fuel?

If it has a computer that controls the timing and the fuel injection, it has an engine management system/engine control unit, regardless of the fuel that is recommended by the manufacturer. Some are just more sophisticated than others.

[pinelakeperch]

Originally Posted by elkhunter11

If it has a computer that controls the timing and the fuel injection, it has an engine management system/engine control unit, regardless of the fuel that is recommended by the manufacturer. Some are just more sophisticated than others.

I'm not entirely sure what point you're trying to make. I completely agree that there is a varying degree of sophistication between engine management systems. A Chevy Cobalt and a Z06 Corvette have differences in sophistication in terms of their respective engine management systems.

[79ford]

Performance comes from compression ratio, anti knock ratings allow the gasoline air mixture to be squeezed tighter the higher they go.

Newer engines can compensate for this by adjusting valve timing etc. The loss or gain in power you see is from the retarding or advancing of cam/valve timing.

The likely hood of detonation goes up because the engine depends on the systems to work and the engine to be in good clean mechanical order. If you dont care about performance there isnt much to gain other than reducing the chance of engine knock if the motor did not perform properly.

[Tactical Lever]

Originally Posted by 79ford

Performance comes from compression ratio, anti knock ratings allow the gasoline air mixture to be squeezed tighter the higher they go.

Newer engines can compensate for this by adjusting valve timing etc. The loss or gain in power you see is from the retarding or advancing of cam/valve timing.

The likely hood of detonation goes up because the engine depends on the systems to work and the engine to be in good clean mechanical order. If you dont care about performance there isnt much to gain other than reducing the chance of engine knock if the motor did not perform properly.

VVT is usually a function of engine speed.

Engine knock is addressed by the knock sensor which then retards the spark. Old tech that's been around forever. Usually trouble shot with a small hammer.

Although it would not overly surprise me to find out someone overengineered a complex solution to a simple problem.

[ssyd]

I hope I'm repeating what I was told by my mechanic correctly but here goes.

Premium fuel contains an additive that reduces the actual compression in the engine to protect consumers' cars from the extra energy generated by higher octane fuels.

I mentioned to him that I had been running premium fuel in my truck to try to make up for the dead cylinder (literally dead, 0 psi) and he explained this to me. He suggested that if I need that extra power to run regular gas and add an octane booster instead.

[Tactical Lever]

Originally Posted by ssyd

I hope I'm repeating what I was told by my mechanic correctly but here goes.

Premium fuel contains an additive that reduces the actual compression in the engine to protect consumers' cars from the extra energy generated by higher octane fuels.

I mentioned to him that I had been running premium fuel in my truck to try to make up for the dead cylinder (literally dead, 0 psi) and he explained this to me. He suggested that if I need that extra power to run regular gas and add an octane booster instead.

Well, I kind of hope you are repeating it incorrectly. Does not sound like someone I would let under the hood.

First, there is no way to reduce the actual compression. It is a fixed ratio dictated by total cylinder volume at bdc and volume left over at tdc.

Octane booster still reduces volatility, which is not what you want, if not required by your engines compression ratio, valve overlap, and to a lesser extent, load, cylinder filling efficiency, rpm and heat.

[rawhide]

Here is what I know and found out using premium fuel.

I ran premium fuel in a 2007 Dodge ram and a 2011 Dodge ram both with the Hemi engines. Also several fleet F350 Super Duty four door long box with the 6.2l gas engines.

In all cases the after a true tally per month added in the receipts and mileage. Running premium did have some benefits. at the end of the month say the fuel costs were pretty close the same, +_ a few dollars. But I did in all cases get better mileage, with the higher fuel costs. Made it running costs the same.

Seat of the pants, was noticeable increase in power. Better for pulling driving uphills, etc.

Oil Changes seemed to be cleaner, don't know why.

Long story short, I do run premium in my personal and work trucks. Have hadn't had issues in the last ten years.


my two cents