[Mongoose]

So here is my situation. I have always used 87octane (the cheapest) gas in my cars (with the exception of my 04 Subaru WRX which calls for 91 to prevent pre-ignition in it's high compression motor). When I bought my CBR250R my dealer says to me "By the way... I would recommend putting nothing less than 89octane in this bike"... so I asked "why, is the compression so high that it will knock?" and he said "no, nothing to do with that.... 87 gas is unregulated".... i asked him to explain and he said "89 is where the oil company starts to regulate gas.... in other words 87 gas might be anywhere from 84-7 octane.... 89 is guaranteed to be 89". This sounds like complete BS but he has been a mechanic for 20+ years! Anyone have any SOLID documentation, links, ect to either disprove this or support it

Just don't wanna waste money on 89 gas if it's no better

BTW... i already know that higher octane is to prevent engine knock/ping/pre-fire on high compression motors so lets not drift into that topic please. The subject is quality of the gas

 

[CeeBeeArr]

I have often wondered about the 'quality' of 87 octane fuel but not the octane number itself. I say that because the check engine light came on in my van after a fillup at the local bargain fuel place. I decided to suspect fuel before taking it in and started running a more name brand fuel. The light went off. As I think about it, the oxygen sensor is probably getting old and that is the likely cause of the light but still, it seems to suggest that not all 'regular' gas is the same.

 

[Mongoose]

it seems to suggest that not all 'regular' gas is the same.

I think this what the dealer was talking about when he said it was not regulated. your light prob came on cause it was making it run poorly. newer or older van?

 

[CeeBeeArr]

I think this what the dealer was talking about when he said it was not regulated. your light prob came on cause it was making it run poorly. newer or older van?

It is 2006 and has about 100k kms on it so that is why I thought of the oxygen sensor.

 

[Mongoose]

It is 2006 and has about 100k kms on it so that is why I thought of the oxygen sensor.

Well the fact that you used cheap gas then used good gas and the light came on and off kinda points to gas as being the problem and not a old or faulty sensor. I asked someone I know that works for a place called griffith oil (heating oil company) and he said they have to periodically test their oil to ensure its a certain octane because the state does random inspections on them. He also said since the addition of ethanol in fuel can lower the octane number.

 

[makaTony]

i never seen 89 octane

 

[Aufitt]

Never seen less than 91 avail and I wouldnt run that in my lawnmower, use 95 or 98 and get way better efficiency, cleaner injector & combustion chamber... you'll notice by the exhaust colour.

Maybe this is the 'Top end rattle' we read about on here?

 

[CeeBeeArr]

Never seen less than 91 avail and I wouldnt run that in my lawnmower, use 95 or 98 and get way better efficiency, cleaner injector & combustion chamber... you'll notice by the exhaust colour.

Maybe this is the 'Top end rattle' we read about on here?

Octane rating - Wikipedia, the free encyclopedia

Australia uses the RON index and Canada uses the MON or AKI index (not sure which). Apparently there are about 4-5 points difference so your 91 is equal to our 86 or 87

As to the rattle, I have tried everything from 87 to 94 (the lower and upper limits here) and find no difference in either noise or performance.

 

[CeeBeeArr]

Well the fact that you used cheap gas then used good gas and the light came on and off kinda points to gas as being the problem and not a old or faulty sensor. I asked someone I know that works for a place called griffith oil (heating oil company) and he said they have to periodically test their oil to ensure its a certain octane because the state does random inspections on them. He also said since the addition of ethanol in fuel can lower the octane number.

Octane rating - Wikipedia, the free encyclopedia

According to this, ethanol raises the octane number.

Still don't get how they can say that pinging and knocking is caused by low octane and high compression and then turn around and say it can be controlled by ignition timing. I do get that it is a full throttle effect because anything else is effectively reducing the engine compression ratio.

 

[Mongoose]

According to this, ethanol raises the octane number.

From wikipedia: "Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced."
Good call dude! As far as knock... let's keep the thread focused on gas quality and/or PON accuracy

 

[ice_burg]

Honda recommends 86 octane for the 08 civic I bought. Talks about it specifically in the manual. I can't imagine the 86 would test any less than it is supposed to unless you are buying right off the barge maybe. Regardless, I have been using 89 in my CBR.

 

[ice_burg]

From wikipedia: "Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced."
Good call dude! As far as knock... let's keep the thread focused on gas quality and/or PON accuracy

So essentially what I am reading is that Ethanol increases octane and simultaneously decreases efficiency. So I can go less distance on my bike per unit of measure of fuel but it will burn at a more constant rate. I will keep buying my non-ethanol blended fuel while I can.

 

[makaTony]

well here we have 95 and 98 versions of gasoline. i think that's the octane value. in popular speech it means that the gasoline is 95% rsp 98% free of lead.

so if you guys are talking about "Ethanol increases octane" i can only say: of course. the more ethanol, the less lead percentage. but that doesn't mean that the fuel quality will get better!?

 

[sendler]

Octane

All of my gas is 10% ethanol which robs fuel economy but I have no choice. I have been running 93 octane so far but have always run 87 in my cars and will also start using that in the Honda which has only moderate compression and should handle it well also. The Ninja has higher compression and doesn't get ridden as much so I will stick with 93 for that.

 

[ice_burg]

All of my gas is 10% ethanol which robs fuel economy but I have no choice. I have been running 93 octane so far but have always run 87 in my cars and will also start using that in the Honda which has only moderate compression and should handle it well also. The Ninja has higher compression and doesn't get ridden as much so I will stick with 93 for that.

Same here. I was just using 89 initially as I have heard it helps engines run cooler. I read in the manual where it says to use 86 or higher. I do have a few gas stations that have pumps for pure 87 as well as 87+ethanol blend in the same dock.

 

[n1kmug]

My dealer said to use 87 and put 93 every couple of fill ups... doesn't make much sense. I just do 93 every time to be safe

 

[Administrator]

The other way to look at it is how big is your tank? its going to cost you what? and extra dollar or 2 to put in good gas per tank.... Dont be cheap

Stew

 

[ice_burg]

I dunno, Honda has all of the R and D in to the bike so if they say 86 or higher I am ok with it... I will just buy from reputable places that I trust.

 

[Mongoose]

The other way to look at it is how big is your tank? its going to cost you what? and extra dollar or 2 to put in good gas per tank.... Dont be cheap

Stew

Good call.

 

[Iryxian]

From wikipedia: "Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced."
Good call dude! As far as knock... let's keep the thread focused on gas quality and/or PON accuracy

How long have you been out of school? No teacher would ever let you cite wikipedia as a source. So quoting it doesn't hold much water.