Gas Treatment

[Ormonddude]

I was going to say the Only reason there is water in the tank in the first place is because it settles under the fuel and then cannot evaporate the fuel evaporates as it isolates the water a empty tank stays empty - at least last I checked LOL

[Phil M]

As a premium gas user for my Honda, I was suprised to watch a Marketplace documentary called Pump Fiction. http://www.cbc.ca/player/ premium gas, to put it bluntly, is a waste of your money, and just another rip off by the oil companies. If you are a premium gas user like I was, you are being mislead on purpose.

[RobertB]

IMHO, premium gas is only a waste if you use it in an engine not tuned to use it. Two of my 3 turbocharged engines are tuned for it and we do indeed notice a real diference. Our 2004 VW Beetle actually has a lower cost per mile running premium. My 2005 volve XC70 has a noticable power difference between regular and premium.

Thank god our 2012 F-150 Ecoboost does not require premium - that 36 gallon gas tank would require a bank loan every fillup.

[Tomfoolery]

Pump Fiction was interesting, but the first bit with the dyno was, um, I'm not sure what it was. Since the dyno is measuring the rate of energy transferred into the dyno itself, with the same car doing the same wheel speed with the same dyno-imposed load, it will measure the same power regardless of the gas used, or even if it was from a collection of hamster wheels. Torque, too. And the cruise control is a closed loop control, maintaining the same wheel speed, against the same resistance, giving the same torque and power into the dyno rollers, again no matter what engine or fuel is used.

Unless I'm missing something.

[mastreb]

For most cars, which have engines targeting an 8:1 compression ratio, Premium is a waste of money.

However, for cars with a compression ratio over 11:1, high octane fuel is a hard requirement and if you don't use it, you will cause knocking, pinging, and can eventually damage your car. The octane rating refers to more complex molecule fuels in admixture that retard the detonation of the fuel so that it won't ignite before the cylinder is at full compression when the engine is hot. Pre-detonation causes both a loss of power and stresses on the engine. As compression ratios go up, the combustibility of the fuel has to go down or it can detonate in the wrong phase.

But all gasoline fuels are blends of complex hydrocarbons from heptane to decane and even other fuel oils, and there isn't anything about the "blend" of premium that makes it inherently more expensive. It used to be that they actually used octane, a particular distillate of crude oil that was a bit rare, but now days they use all kinds of distillates and testing to just get to a point of combustibility that is just referred to as octane.

These days, it simply costs more because it goes into more expensive engines that are owned by people who will pay more. That's literally the only reason.

But most cars do not have high compression ratio engines. There are no other significant benefits and the detergents are the same in most grades these days.

The bottom line is, read your service manual and use the MINIMUM octane they recommend for your engine.

http://en.wikipedia.org/wiki/Octane

http://www.scientificamerican.com/artic ... -premium-g

[seahouse]

Actually, a modern high-compression engine that is not run on premium will not be damaged by the use of regular fuel. Been there, done that, when on a trip premium was not available, I had to put a tank of regular in (a high-compression, dual overhead cam, V8).

Mounted in the engine block is a device called a knock sensor(s) which detect(s) the shock waves that result from knocking and retards the timing (among other things) until it is eliminated. Of course, retarding the timing has an accompanying loss of performance and fuel economy, so your mileage drops as a result. Also, retarding the timing can only be done within certain limits, so if I were loading the engine by, say, towing a trailer, in hot weather, I would not want to run regular in an engine designed for premium fuel for any length of time. IIRC, Corvettes had knock sensors mounted in the blocks in the early 90's, or maybe even before.

It is absolutely correct that there is no advantage to running high-octane in a vehicle not made for it. With some exceptions. One is if there is a carbon buildup on the piston (more common in days gone by) and combustion chamber, which will effectively increase the compression ratio of the engine. So some older vehicles will need to run high-test to prevent engine damage.

Another, as I have mentioned in another recent thread, is to compensate for octane level drop during storage periods.

Another is that if there is some component in the fuel system, that is sensitive to ethanol, or if you just don't want the problems associated with using ethanol as a fuel. Premium fuel (at least in Canada, and for the time being) is not diluted by ethanol. Of course, ethanol in fuel will reduce fuel economy.

Good advice mastreb -your owner's manual will tell you whether premium is suggested, or required, and will give you the octane ratings recommended.

I'm going to end this post before I think of other reasons, or I'll be up all night.

-B.

Also note that a high compression characteristic gives better energy efficiency in an engine, and considerable research technology has recently been brought to bear on raising compression, while still maintaining the requirement for regular fuel. The Ford Eco-boost technology is one that comes to mind, but other manufacturers are working on the same problem and have their own versions.

[seahouse]

Just watched pump fiction. Not much new info there, but some really bad journalism. I must say, I have never seen (in Canada) any oil company advertisement saying that running premium fuel in a car that needs regular is a benefit (I'm sure someone will show it to me if I have missed it). Of course, if you consider gas station attendants* to be reliable sources for such technical information, as they have in the show, then you deserve the melange of answers you get. Dohhhh!

As previously pointed out, they have drawn some conclusions on some REALLY unscientific tests there too. It's less common than it used to be, but a lot of these programmes could do well to have a technical advisor on hand, if accuracy were of concern to them.

In the dyno test they showed us only the HC tailpipe emissions- only one of three, or more, emissions measured. Nitrogen oxides, which result from high peak combustion temperatures, are also tested for, and would have been lower with higher-octane gas, but they were not shown. The reporters show the people and things that illustrate one point of view only, and edit out those interviewees and facts which contradict their viewpoint. Unbalanced journalism, and totally hypocritical because they themselves are doing exactly what they are accusing the oil companies of doing- misrepresentation. (Can this be possible - did I just hear myself defending the big oil companies?) Never thought that would happen.

I could go on, and please excuse my sceptical attitude, but the show did not present any new evidence or information that was not available to anyone before. In fact, all that info was as close as the owner's manual in the glove compartment. Dohhh! RTFM!

-B.

I would add though, that if your car calls for regular, but you find it does need to burn premium in order to run well, then that is a sign that some repairs are likely required.

*(Not that there's anything wrong with being a gas station attendant, of course).

[finding41]

Seahouse you mentioned that the premium gas in Canada doesn't have ethanol in it. You must get fuel at Shell. I have noticed they are the only ones that don't have ethanol in there premium. I looked around last spring and Shell was the only in London Ont. All the stations had a lower amount of ethanol in the premium than the "up to 15%" in regular.
I have read and seen first hand the problems with ethanol in small engines. All my small engines from lawnmower to gas compressor etc now run on premium from Shell only. The fleet captain at our yacht club mentioned at the last meeting that we are going to switch fuel suppliers for the clubs safety boats and barge. This after having put carb kits in each motor (4) for the last 3 years running.
I haven't seen Pump Fiction yet. But may in the future.

[seahouse]

Hey Finding41!

They don't make it easy for us consumers, and we're constantly shooting at a moving target. Not too long ago, none of the premium fuels had ethanol in them, it was added to the lower grades to boost octane rating. Actually I use Esso, but the local Canadian Tire gas bar has no ethanol in their premium, and (I think) maybe not in their regular either. Even from the same brand label, gas blends do vary by region, by season, and over time.

The link below might be helpful, but check the entry dates - the information is outdated the day they decide to add ethanol to a new brand/grade. And the local Gale's gas bar doesn't pump premium at all, just regular (although their premium is listed as ethanol-free).

I can't give you exact numbers because I don't pay as much attention to it as I should, but the price spread between regular and premium has been more than twice in Canada (60 - 80 cents a gallon here) than in the USA. (I'm fairly close to the border and sometimes gas up when there). And most of the gas you buy near the border in the US at a (sometimes much) lower price originated in Canada - another annoying thought for the day. Just in case you needed one.

http://www.pure-gas.org/index.jsp?stateprov=ON

-Brian.

[mastreb]

Hey Seahouse read a 2 stroke Manual NO ALCOHOL just because something appears to Mix don't mean it didn't destroy lubrication properties - Water will mix with gear oil in your foot that does not mean the water is not a negative effect. its the same principal

Just checked the manual for my two-stroke. It says ethanol 10% is perfectly fine.

http://www.evinrude.com/en-CA/engines/E ... _60_INLINE

Earlier two strokes were not compatible with ethanol because they used plastics incompatible with ethanol as fuel system components, not because oil and ethanol don't mix.

In fact, ethanol is a bit of a wonder admixture. It allows oil, gasoline, and water to blend into solution perfectly, which is why its used as engine treatment--it causes water that would otherwise be insoluble to blend into the gasoline and go through the combustion cycle without interrupting it.

The widely reported problems with ethanol during the transition to ethanol come down to two causes: 1) Its such a good detergent that it cleaned the insides of old gunky fuel tanks causing gunk to go into solution and foul engines, and because there are a number of plastics that are dissolved by it, and some of those plastics were common fuel hose and system components.

Those days are long gone. The advantages to using ethanol in solution with gasoline are numerous (it keeps impurities in solution so gunk doesn't build up, and it keeps water in solution to prevent water fouling and increase the longevity of gasoline in humid environments, it promotes complete burn by oxygenating the gasoline which avoids the use of the far more dangerous toxin MBTE, &c.). The only actual issue with it is that is is hydrophilic and will preferentially bind moisture out of the atmosphere and can become water saturated in very humid areas when it's left exposed to air. But that's it.

These properties have a lot to do with why engines last twice as long these days as they did twenty years ago.

Matt

[raycarlson]

finally masterb, someone actually knows about what alchohol and gasoline do with eachother.Every time i hear about ethanol being harmful to an engine it makes me want to barf,its not the ethanol thats harmful,its poor maintenance practices by the operator that does the harm,virtually any engine made since the 1980's has fuel systems desigtned to run with ethanol blends,but its the operators responsibility to keep the water out of the system,so with poor maintenance practices water is let into the system and now you start having problems,which then is blamed on the ethanol.Like i've said before here in AZ we've have had all gasoline at 10% blend since 1978 with no problems whatso ever,probably due to the lack of any humidity,so no moisture accumulates in the tanks.and the reason for the ethanol in the fuel has nothing at all to do with raising octane level,in the U.S. it is added for anti-pollution measures to reduce NOX, and CO levels.All my manuals also include a statement regarding approval for 10% blended fuel.never seen any engine manual saying never to use any type of blend in it,that would be interesting to see what type of engine that was and what year of manf.

[Dimitri-2000X-Tampa]

Yea, I think most of these additives are pump fiction too...lol The PO of my boat used to use additives all the time and when I ended up with blocked carbs, I found particles the same color (red) as the additives lining the inside of the hoses, and blocking up the carb jets. I had two blocked carb issues in the first few years of ownerships and then switched to my method.

What is my method? Well first, I don't let fuel sit in my tanks for too long (because I like to use my boat a lot) but I also don't dump it out...I just use it up within a few months at most, secondly, I don't use any additives any more, and thirdly, I got a spin-on water separating fuel filter a few years back. Since then, my carbed motor has run flawlessly. In fact, I just changed out the filter for the first time, which I just threw away because it had about 3 tablespoons of water in the bottom of it which did not get into my motor. Man, that was easy! And the new filter probably cost less than a bottle or two of additives! Those stock inline (paper) filters don't do squat for water.

I also installed a valve so that I can easily switch between tanks when one runs dry...that sure is a lot better than squirting gas onto my hands messing with those quick connect fittings when my engine abrubtly runs out of gas in a busy channel full of high speed powerboats!

[mastreb]

Well, the first 24 gallons of gas I put in my Mac 26M in San Diego was typical 10% ethanol from a roadside Shell station. (high humidity) lasted 18 months. Towards the end, I was starting to get some sputter from absorbed moisture.

Next 24 gallons is pure non-ethanol gasoline from a marina fuel depot that only cost 2.5X as much. I'll report how it goes through, again it will likely last 18 months.

My engine is instrumented via an NMEA2000 cable, so I'll be able to report any discrepancy in fuel usage as well as fuel longevity.

Matt

[mastreb]

finally masterb

Well, at least you didn't call me "masturb"

[Ixneigh]

Re water separator
I had a canister spin on type but corrosion was a problem. I replaced it with a plastic filter. I though to maybe trim the fuel uptake tube in the gas tank by a half inch instead and dump out any water once in a while. Thought?