Over on the "break-in period sucks" thread, someone mentioned the paranoia of whether or not you're actually getting "premium" gas, especiall when it all comes from the same nozzle.

Some of you may remember, last week I complained that my MINI seemed to be running rather rough and getting awful (mid to high teens) mileage. Upon further research, my symptoms were consistent with people who have tried running a tank of regular gas through their MINI.

Fast forward to this week. I filled up at a brand name (not really, Quicktrip... but they "gaurantee" their gas, whatever that means) station instead of my regular trip to the discount supermarket station. Surprisingly, my MINI is running *much* better. Smoother acceleration with none of the "rough" feeling of before, and mileage in the more reasonable 23-24mpg range.

My question is this... is there any way to "test" gas to see what octane it truly is? I have a sneaking suspicion it may not actually be the 93 octane advertised...

 

I've gotten tankfulls at "major" brand names that seem to come up short, though I have no way to prove this. A quick dip-stick like item you stick down your filler tube that samples the fuel would be awesome.

MOTOR'N is the only gasoline chemist I know of. If he sees this, hopefully he can provide some insight.

Back to my theorization; I've found certain cars "like" certain brands of gas. Not sure if I'm hallucinating or if there is a tangible difference that works with some engine configs and not as well with others. For example, I've found that my MCS loves Sunoco fuel.

 

Heh.

I'm actually planning to try yet another brand this week and see if the trend continues....

If what I experienced last week was truly "regular" gas in a MINI, I can (without any reservation) say THE MINI ABSOLUTELY NEEDS PREMIUM GAS. I'm sure that has been said before, but now I know WHY :smile:

EDIT: In addition to the rough operation, it occured to me that the ~$2.00 you would save on regular gas would be MORE than eclipsed by the abysmal mileage.

 

What about ethenyl in Sunoco? Is that good/bad?

 

Most petro companies put ethanol in our gasoline nowadays, 10% is typical. I'm not sure if this is a performance helper or not, but I do know that alcohol's burn much colder than gasoline. Might help at the dyno, hmmm.

 

>>Most petro companies put ethanol in our gasoline nowadays, 10% is typical. I'm not sure if this is a performance helper or not, but I do know that alcohol's burn much colder than gasoline. Might help at the dyno, hmmm.


There is no quick way to measure octane. first of all to measure the octane number you get here in the US, tyou need to methods......that R+M/2 sign near the octane number often seen in US gas stations means that the RESEARCH Method number is ADDED to the MOTOR Method number and divided by , you guessed it, 2.
What is research method? Every component of gasoline has a theoretical octane number calculated from its relative chemestry as compared to PENTANE (which is a component that has an octane rating of 100). If you have a fuel with 6 different streams of hydrocarbons and you know (as you do in a refinery) the calculated value of these streams, then you can calculate the Octane number. this number tends to be high.
The MOTOR method, as the name implies, measures the tendency of the blend to create knock on a single cylinder research engine. The baseline is again, the afore mentioned PENTANE. This number tends to be lower......thus the average and we can all talk the same language.
PREMIUM fuel is not only about octane however......the very serious brands like Shell, Amoco (BP), ChevronTexaco do special formulas with "better" components....your chances of getting these special fuels decrease the further away you are from a refinery......If I lived in LA for instance, I would tend to want to use Chevron (El Segundo Refinery), etc.......
the other differentiator is the amount of intake valve cleaning detergents in the fuel. Premium from big brands tends no have better and more additive. All gasoline is required to use these additives but the EPA (in its wisdom) came up with a minimum additive concentration requirement and guess where most gasoline sold is?

 

>>Most petro companies put ethanol in our gasoline nowadays, 10% is typical. I'm not sure if this is a performance helper or not, but I do know that alcohol's burn much colder than gasoline. Might help at the dyno, hmmm.


There is no quick way to measure octane. first of all to measure the octane number you get here in the US, tyou need to methods......that R+M/2 sign near the octane number often seen in US gas stations means that the RESEARCH Method number is ADDED to the MOTOR Method number and divided by , you guessed it, 2.
What is research method? Every component of gasoline has a theoretical octane number calculated from its relative chemestry as compared to PENTANE (which is a component that has an octane rating of 100). If you have a fuel with 6 different streams of hydrocarbons and you know (as you do in a refinery) the calculated value of these streams, then you can calculate the Octane number. this number tends to be high.

The MOTOR method, as the name implies, measures the tendency of the blend to create knock on a single cylinder research engine. The baseline is again, the afore mentioned PENTANE. This number tends to be lower......thus the average and we can all talk the same language.
PREMIUM fuel is not only about octane however......the very serious brands like Shell, Amoco (BP), ChevronTexaco do special formulas with "better" components....your chances of getting these special fuels decrease the further away you are from a refinery......If I lived in LA for instance, I would tend to want to use Chevron (El Segundo Refinery), etc.......
the other differentiator is the amount of intake valve cleaning detergents in the fuel. Premium from big brands tends no have better and more additive. All gasoline is required to use these additives but the EPA (in its wisdom) came up with a minimum additive concentration requirement and guess where most gasoline sold is?
On ethanol......it is really not very good for your car. It does have a high octane number, and it contains oxygen which is marginally good for pollution control however like all "ols"....it LOVES water and has some......it also attracts water AFTER it is "dried" and most worrisome, it encourages the formation of nasty deposits on you intake valves which later get moved into the top of your piston which in turn leads to a higher than designed compression ratio and that is why old cars ping like mad regardless of what you put in them........sorry.....got carried away here....

 

>> A quick dip-stick like item you stick down your filler tube that samples the fuel would be awesome.
>>


I would very much like to have something like that. Especially when paying $1.98 a gallon for 93. I normally use Texaco as it is convieniant but in a vehicle I owned before the MINI, if I used a certain station, my mileage was worse. It was one of the cheaper than everyone else stations.

Anyway, back to my main reason for posting. I wonder if it would be possible to have some sort of litmus type test for seperate grades of gas.

 

Don't think there is any litmus test. Just buy from a reputable (and nationally recognized brand) gas station. Out on the West Coast, I like Chevron and Shell.

 

Buy regular and don't worry about it, then if you get premium instead, it'll be a pleasant suprise !

 

>>>> A quick dip-stick like item you stick down your filler tube that samples the fuel would be awesome.
>>>>
>>
>>
>>I would very much like to have something like that. Especially when paying $1.98 a gallon for 93. I normally use Texaco as it is convieniant but in a vehicle I owned before the MINI, if I used a certain station, my mileage was worse. It was one of the cheaper than everyone else stations.
>>
>>Anyway, back to my main reason for posting. I wonder if it would be possible to have some sort of litmus type test for seperate grades of gas.

$1.98 for 93 octane? We're paying $2.30 for 91 in Hawaii.

 

>>$1.98 for 93 octane? We're paying $2.30 for 91 in Hawaii.

Oil companies are scared to raise it that much here in Alabama. They know we will fire up the old stills and make our own alternative fuel.

 

>>>>$1.98 for 93 octane? We're paying $2.30 for 91 in Hawaii.
>>
>>Oil companies are scared to raise it that much here in Alabama. They know we will fire up the old stills and make our own alternative fuel.
A friend just moved back to North Carolina and he said his grandpappy still has a hemi cuda set to run on moonshine. Or was it to run moonshine?

 

>>>> A quick dip-stick like item you stick down your filler tube that samples the fuel would be awesome.
>>>>
>>
>>
>>I would very much like to have something like that. Especially when paying $1.98 a gallon for 93. I normally use Texaco as it is convieniant but in a vehicle I owned before the MINI, if I used a certain station, my mileage was worse. It was one of the cheaper than everyone else stations.
>>
>>Anyway, back to my main reason for posting. I wonder if it would be possible to have some sort of litmus type test for seperate grades of gas.

I've noticed the same thing too.. I keep most of my gas receipts and write the mileage on it.. I used to drive a honda and always Texaco gas gave me the best mileage.. sometimes 20 miles vs. other stations with the same amount of gas. Car seemed to run best on Shell but the mileage was less.

My regommentation is to always go to a busy gas station that is BUSY.. such as near a highway.. That way you will always get the freshest gas! And if you get good mileage and the car doesn't run rough... Continue going there to fill up! Otherwise search on....

 

With no data to back me up, I prefer Chevron/BP, Texaco, or Shell. I avoid any generic stations.

My brother in law drove in MINI last weekend and was nice enough to fill my talk halfway before returning it to me. I immediately noticed that my MINI did not run as well as it should and am positive that he did not fill up with Premium.

So at least I have an idea of what a bad tank of gas will feel like if I get another one.

 

Little tip......highest octane is Shell.......they give you an extra number, all the time.
Trick is to KNOW that the Shell station gets its fuel from a Shell refinery. Ya see, most gas moves through pipelines....everybody puts their fuel into the tube and gets out the mixture at the other end........