what is the best gas?

[Gracie09]

Where'd you hear that about testing the fuel in the tank? A real test involves using a comparison to a reference fuel composed of iso-octane and heptane, and these can only be tested by applying real conditions on a physical setup.

What an engine computer can do is use the knock sensor to detect the onset of knock and retard timing to prevent knock from getting excessive. It's a reactive system that's always adjusting. There's the possibility of a poor mixing of fuel in the tank and the effective octane rating changing as different fuel is taken into the fuel system.

An engine computer can definitely record when maximum retardation of timing is encountered. That would be pretty bad. However, it's unlikely for a modern engine to get to that point.

That would be my cousin who is a mechanic that works exclusively on bmws after going through their training programs. They do it in his shop when the customer complains about performance issues that typically are caused by using the wrong fuel.And my husband who is a hobby gear head but has cool tools like the computer that reads the codes.

 

[bcla]

That would be my cousin who is a mechanic that works exclusively on bmws after going through their training programs. They do it in his shop when the customer complains about performance issues that typically are caused by using the wrong fuel.And my husband who is a hobby gear head but has cool tools like the computer that reads the codes.

I have an OBDII code reader myself. Here's BMW specific codes:

http://www.obd-codes.com/trouble_codes/bmw/

Some of the generic trouble codes are for a "fuel composition sensor", but that's for flex fuel vehicles that use up to E85.

http://www.obd-codes.com/trouble_codes/

There are just way too many variables that go into octane rating that it's impossible to test it without some sort of engine test. A test against a reference fuel is ideal, but there are also variable compression ratio engines that can do it.

Modern engines always adjust on the fly with a knock sensor and timing retardation. If the limits of timing retardation are reached, there are 12 trouble codes for "Cylinder #x Above Knock Threshold". That might indicate that the fuel is inadequate, but it's not testing the fuel, but measuring how much knock. It wouldn't be measuring the fuel, but reporting the consequence of inadequate fuel. I don't know what was explained to you, but it sounds like an oversimplification.

 

[bcla]

Here's a forum where someone asked BMW:

http://forum.roadfly.com/threads/12615839-BMW-explains-using-lower-Octane-gasoline
Thomas Plucinsky, BMW Product and Technology Communications Manager told us all BMW engines are designed to run on 91 octane. All performance testing, including EPA emissions and fuel mileage, is done with 91 octane. However, though BMW is all about performance, their motors will run on 89 or 87 octane without damage. The knock sensors pull the ignition timing back and eliminate detonation. There will be a loss of power and a decrease in fuel mileage, but the size of the horsepower loss and the increase in fuel consumption depends upon many factors, such as ambient temperature, exact formulation of the fuel and driving technique, so BMW does not offer any estimates for operation on lower grade fuels. One not so obvious concern, Mr. Plucinsky noted, is the type and quality of additives the gasoline companies include in the fuel. Premium gasolines may have better additive packages which are more effective keeping fuel systems (particularly injectors) clean and working efficiently, than those in regular grade fuels or off-brand products. Using lower octane or off-brand fuel could be degrading the fuel system over time, setting you up for a repair bill down the line.​

 

[Big V]

I was told by a mechanic to use premium fuel in my small engines like lawn mower and snowblower. Does that make sense? He said the ethanol they put in regular gas is not good for the small engines.

 

[IndyRnRfan]

I was told by a mechanic to use premium fuel in my small engines like lawn mower and snowblower. Does that make sense? He said the ethanol they put in regular gas is not good for the small engines.

If you are lucky to have a gas station that still carries gas without 10% ethanol then use that gas. Just because you select higher octane doesn't mean it will not have ethanol. For example, I have a 66 gas station (no ethanol at all) and a Mobil gas station (10% ethanol). It doesn't matter the octane, we have 87,89,91 with some carrying 93. If that brand uses ethanol, it will be in all octane ratings. And by law I believe it has to say on the pump if the gas contains ethanol.

You will get a mix of reviews on ethanol but in general ethanol gets a bad rep because it is hygroscopic and water is not good in your gas. There are a ton of variables you can throw in the mix which backs up both arguments. It is great for building horsepower, keeping combustion chambers clean, usually cheaper than regular gas but then your engine needs to be programmed to run on it(e85)and flex fuel cars are not specifically programmed to do so or you will loose more money then running regular most of the time, etc... If you run it in a small engine use a stabilizer unless you are going through a tank of gas quickly like every week or two. If your running through a tank every month or so then a stabilizer is a good option and make sure it is specific to ethanol blend gas. Also, with small engines, a little water isn't going to be very terrible. Could cause a little hard start but your carburator will pump the water through as long as it is very little. On fuel injected motors the water can not pass through the injectors and causes problems.

 

[Gumbo4x4]

I was told by a mechanic to use premium fuel in my small engines like lawn mower and snowblower. Does that make sense? He said the ethanol they put in regular gas is not good for the small engines.

Ethanol boosts octane & where sold it is definitely NOT kept out of "premium" gas. In fact, when they started using it here, it was ONLY used in premium.

The "issue" with Ethanol is it can attract moisture. This isn't an issue in daily driven cars, but can cause problems in engines that aren't run on a regular basis - like lawn mowers, snow blowers, race cars, boats, basically anything that isn't used year round.

 

[Ladygoldenhair]

No, premium is only good for cars that require it.

Premium doesn't mean better and agree it could make your car worse. If you are concerned I would look for Ethylene free gas, they tend to add a % in. Or if you do not like using the 87 grade, I will get a 89, but don't go any higher. Sometimes I do top off the tank with $10 of the 89 grade. My new car is a Primium only and I do use SAMs Club or Sunoco gas. I still like to stop at the main company names like Mobile, Sunoco etc instead of US, Star, Dandy, et al.

 

[daughtersrus]

Not better, not worse, just different. All new cars* by law have to run on regular without damaging the engine, but some automakers recommend premium for better performance.

*Only new cars exempt to the regular gas rule are those that less than 500 will be sold in the U.S. ( exotics like Ferrari, Maserati, Lambordini).

That's not true. Edmunds has a long list of cars that require premium.

http://static.ed.edmunds-media.com/unversioned/img/pdf/premium.gasoline/premium.required.071515.pdf

 

[bcla]

I was told by a mechanic to use premium fuel in my small engines like lawn mower and snowblower. Does that make sense? He said the ethanol they put in regular gas is not good for the small engines.

I'm not an ethanol hater, but small engines are another matter. If you're a commercial user, the fuel isn't in the tank long term. But a home user stores the equipment and gives enough time for things like water absorption. Small engines also aren't positively sealed like in cars and air (with water vapor) gets in the tank. I've personally seen phase separation in a small engine's fuel tank. The ethanol/water mixture separates from the hydrocarbons.

 

[bcla]

That's not true. Edmunds has a long list of cars that require premium.

http://static.ed.edmunds-media.com/unversioned/img/pdf/premium.gasoline/premium.required.071515.pdf

That's not what he said. They're required to be able to run on regular without damage. That the manufacturer refers to it as "premium required" is another matter. The specs themselves refer to "recommended fuel". I found the owners manual for the first car on the list:

http://owners.acura.com/vehicles/information/2016/MDX/specs#mid^YD3H2GJNW
http://techinfo.honda.com/rjanisis/pubs/QS/AH/BZ51616OG/enu/BZ51616OG.pdf

It's on page 114:

Use of unleaded premium gasoline of 91 octane or higher is recommended. ​

 

[SkaGoat]

From actual experience, my 2011 Nissan Juke is premium recommended. But you can run regular in it. The big dictractor I noticed is, sure the regular is a little cheaper, but my gas mileage nose dives when using regular, so in the long run, it's cheaper to buy Premium for my car.

Most modern cars will adjust the timing if knock is detected. The manufacturer has no way to prove you used regular, they can only diagnose if the engine has been knocking (as that info is part of OBD II).

 

[Kellykins1218]

The best gas is helium. It makes you talk funny.

 

[bcla]

The best gas is helium. It makes you talk funny.

N2O makes you think funny.

 

[Kellykins1218]

True. On helium you amuse yourself. On Nitrous you amuse everyone else.

 

[dadtoagirl03]

My best gas comes after a trip to Taco Bell!

 

[daughtersrus]

f

That's not what he said. They're required to be able to run on regular without damage. That the manufacturer refers to it as "premium required" is another matter. The specs themselves refer to "recommended fuel". I found the owners manual for the first car on the list:

http://owners.acura.com/vehicles/information/2016/MDX/specs#mid^YD3H2GJNW
http://techinfo.honda.com/rjanisis/pubs/QS/AH/BZ51616OG/enu/BZ51616OG.pdf

It's on page 114:

Use of unleaded premium gasoline of 91 octane or higher is recommended. ​

http://www.fordservicecontent.com/F...350-Supplement-version-1_su_EN-US_07_2015.pdf
Octane Recommendations

Premium unleaded gasoline with an (R+M)/2 octane rating of 91 or higher is required. Ford Performance recommends using unleaded gasoline with octane rating of 93 or higher for optimal performance of this vehicle.

Recommended fuel is an important part of the proper maintenance and optimal performance of this vehicle. The use of gasoline with an octane rating lower than 91 can lead to severe mechanical damage to your vehicle, may degrade vehicle performance, and may affect your warranty coverage.


http://www.ownerinfo.landrover.com/document/3A/2016/T23579/19105_en_GBR/proc/G1800074

OCTANE RATING

NOTE:
Federal law requires that gasoline octane ratings are displayed on the fuel pumps.

Vehicles with a gasoline engine require the use of premium unleaded gasoline, with a minimum octane rating of 91 AKI (Anti-Knock Index). This contributes to increased vehicle performance, fuel economy and driveability.

If premium unleaded fuel is not available, then use unleaded fuel with a lower octane rating, down to a minimum of 87 AKI. The lower octane rated fuel may reduce engine performance, increase fuel consumption, cause an audible engine knock, and other driveability problems.

CAUTION:
Do not use fuels with an octane rating lower than 87 AKI as severe engine damage may occur.

Consult a retailer/authorized repairer if a heavy persistent engine knock is detected, even if using fuel to the recommended octane rating. Particularly if an engine knock is detected, while holding a steady speed on level roads. Failure to do so is misuse of the vehicle, which is not covered by the vehicle's warranty.

NOTE:
An occasional light engine knock when accelerating or climbing hills is acceptable.

CAUTION:
Do not use leaded fuels, fuels with lead substitutes (e.g. manganese-based), or fuel additives. These may adversely affect the emissions control systems, and may affect the vehicle's warranty.

RELATED INFORMATION

 

[bcla]

f
http://www.fordservicecontent.com/F...350-Supplement-version-1_su_EN-US_07_2015.pdf
Octane Recommendations

Premium unleaded gasoline with an (R+M)/2 octane rating of 91 or higher is required. Ford Performance recommends using unleaded gasoline with octane rating of 93 or higher for optimal performance of this vehicle.

Recommended fuel is an important part of the proper maintenance and optimal performance of this vehicle. The use of gasoline with an octane rating lower than 91 can lead to severe mechanical damage to your vehicle, may degrade vehicle performance, and may affect your warranty coverage.

The 2015 Ford Shelby GT350 had production run of 137 cars.

 

[Domo]

The best gas is the stream of knowledge that comes from my mouth

 

[daughtersrus]

That's not what he said. They're required to be able to run on regular without damage. That the manufacturer refers to it as "premium required" is another matter. The specs themselves refer to "recommended fuel". I found the owners manual for the first car on the list:

http://owners.acura.com/vehicles/information/2016/MDX/specs#mid^YD3H2GJNW
http://techinfo.honda.com/rjanisis/pubs/QS/AH/BZ51616OG/enu/BZ51616OG.pdf

It's on page 114:

Use of unleaded premium gasoline of 91 octane or higher is recommended. ​

If equipped with the LT4 supercharged engine, use premium

unleaded gasoline meeting ASTM specification D4814 with a posted octane rating of 91 or higher. If the

octane is less than 91, damage to the engine may occur and may void the vehicle warranty. If heavy knocking is heard when using

gasoline rated at 91 octane or higher, the engine needs service.


https://www.chevrolet.com/content/d..._pdf/2016-corvette-stingray-owners-manual.pdf



! Only refuel using unleaded premium grade gasoline with at least 91 AKI/95 RON.
https://www.mbusa.com/mercedes/service_and_parts/owners_manuals#!year=2016&class=E-Cabriolet


If the vehicle has the 3.6L V6 twin turbo engine, use premium unleaded gasoline meeting ASTM specification D4814 with a posted octane rating of 91 or higher. If the octane is less than 91, damage to the engine may occur and may void the vehicle warranty.

http://www.cadillac.com/content/dam...eos/03_pdf/2016-atsv-coupe-owner-manual-2.pdf

 

[SkaGoat]

If equipped with the LT4 supercharged engine, use premium

unleaded gasoline meeting ASTM specification D4814 with a posted octane rating of 91 or higher. If the

octane is less than 91, damage to the engine may occur and may void the vehicle warranty. If heavy knocking is heard when using

gasoline rated at 91 octane or higher, the engine needs service.


https://www.chevrolet.com/content/d..._pdf/2016-corvette-stingray-owners-manual.pdf



! Only refuel using unleaded premium grade gasoline with at least 91 AKI/95 RON.
https://www.mbusa.com/mercedes/service_and_parts/owners_manuals#!year=2016&class=E-Cabriolet


If the vehicle has the 3.6L V6 twin turbo engine, use premium unleaded gasoline meeting ASTM specification D4814 with a posted octane rating of 91 or higher. If the octane is less than 91, damage to the engine may occur and may void the vehicle warranty.

http://www.cadillac.com/content/dam...eos/03_pdf/2016-atsv-coupe-owner-manual-2.pdf

Notice the large MAY in every one of those examples. Those are all to cover their butts.