Spreaders of Conspiracy Theories: Unmasking the Motivations Behind the Lies

[lennya12threh]

Previously I thought 91 was better than 95. Then I saw some prices and found that the Benzyne 95 was more expensive than the 91.....

Whats this?

And what does the 95 and 91 stand for?

Which is better?

[SeanMoran]

It's the octane rating. If you love your little Honda, then feed her 95, but generally standard bikes run okay on 91.

[lennya12threh]

It's the octane rating. If you love your little Honda, then feed her 95, but generally standard bikes run okay on 91.

Well I didnt know it was the octane rating....

Mine is a Suzuki gsxr750.. There is a sticker on the side saying something about 95 or higher octane....

[neverdie]

Relates to the octane of the fuel. High compression engines require a higher octane to stop pre-ignition and so engine knock which can be damaging. Look in your hand book, if it says 91 then use it, save some cash. Some hand books say use any grade, theres no benefit paying for higher octane if not needed.

Whilst I agree with most of what you have said, I disagree with the highlighted section above as I have always found that my vehicles will actually get a slightly higher rate of mileage out of the 95 octane or high stuff than the standard 91.....just my two satangs worth.

[SeanMoran]

Well I didnt know it was the octane rating....

Mine is a Suzuki gsxr750.. There is a sticker on the side saying something about 95 or higher octane....

GSXR-750 has been the bike of my dreams since I was a kid unpacking cartons at a motorbike shop in school holidays in around 1984 or thereabouts.

I was thinking more about the 4-stroke or 2-stroke 100-125 sort of Thai bikes (2-strokes use autolube so not likely that a 4% octane difference would cause detonation when the autolube would have the same effect as increasing the octane rating), but if it's the coolest roadbike ever invented; the GSXR-750, then I'd imagine that deep inside those four chambers of her high-revving heart she would solemnly encourage you to abide by the doctrines of that sticker, and it's less confusing to the bowser boy if he has to make a decision when he sees you rock up on a bike like that.

Gao-sip Haa!

[junkofdavid2]

I can only speak for gasohol and not benzene.

I've extensively experimented on both Gasohol 91 and 95 on my 1995 Toyota Camry, and I get much more knocking on acceleration and worse fuel economy (more than 10% more fuel consumption) when I use Gasohol 95 instead of 91.

In other words, 91 one is much better with my car, despite the fact that it's more than 1 baht cheaper per liter.

I later read several sites which say that despite the advertising of companies which push for their "higher octane premium" fuel, "higher octane" is not always better... but rather, that the best octane rating is the one closest to your car specification... and in my case, it's 89.

*I use Shell. I also had horrible mileage and bad power (car would feel "heavy") when I would load from an old PTT station in our soi which is now closed. Could've been the station and not the brand though. I also feel that as a multinational company, Shell would probably be less likely to award dealerships based on "family connections."

One of the biggest challenges to quality control in the gas station industry, I gather, is the difficulty in policing the dealers (making sure they don't "mix" other "extenders" or fillers into the fuel for extra profit, etc.).

How is the mother company inspector going to threaten a dishonest dealer with shut-down, if he is the "relative"of one of the company big-shots?

[katabeachbum]

It's the octane rating. If you love your little Honda, then feed her 95, but generally standard bikes run okay on 91.

Well I didnt know it was the octane rating....

Mine is a Suzuki gsxr750.. There is a sticker on the side saying something about 95 or higher octane....

95 benzene, no gasohol/E10/E20 please. 95 benzene is available at Shell, called VPower.

[SeanMoran]

Well I didnt know it was the octane rating....

Mine is a Suzuki gsxr750.. There is a sticker on the side saying something about 95 or higher octane....

GSXR-750 has been the bike of my dreams since I was a kid unpacking cartons at a motorbike shop in school holidays in around 1984 or thereabouts.

I was thinking more about the 4-stroke or 2-stroke 100-125 sort of Thai bikes (2-strokes use autolube so not likely that a 4% octane difference would cause detonation when the autolube would have the same effect as increasing the octane rating), but if it's the coolest roadbike ever invented; the GSXR-750, then I'd imagine that deep inside those four chambers of her high-revving heart she would solemnly encourage you to abide by the doctrines of that sticker, and it's less confusing to the bowser boy if he has to make a decision when he sees you rock up on a bike like that.

Gao-sip Haa!

[Pikey]

Well I didnt know it was the octane rating....

Mine is a Suzuki gsxr750.. There is a sticker on the side saying something about 95 or higher octane....

GSXR-750 has been the bike of my dreams since I was a kid unpacking cartons at a motorbike shop in school holidays in around 1984 or thereabouts.

I was thinking more about the 4-stroke or 2-stroke 100-125 sort of Thai bikes (2-strokes use autolube so not likely that a 4% octane difference would cause detonation when the autolube would have the same effect as increasing the octane rating), but if it's the coolest roadbike ever invented; the GSXR-750, then I'd imagine that deep inside those four chambers of her high-revving heart she would solemnly encourage you to abide by the doctrines of that sticker, and it's less confusing to the bowser boy if he has to make a decision when he sees you rock up on a bike like that.

Gao-sip Haa!

Autolube will have stuff-all effect on the octane rating as it relates to oil being automatically injected into the fuel/air mix.

Someone mentioned using the octane closest to what the manufacturers owner manual says and I'd agree. There is no point in putting 95 in an engine designed to run on 91. You won't get anymore power out of the higher octane. In fact in a lot of cases, you will get less because the engine will have a lower compression ratio and will not squeeze the mix enough to ensure a full burn. For the Gixxer, check the manual and if it needs higher than 91, I think Shell V Power is the only option nowadays for straight petrol as all the other 95s I have seen have been E10 gasohol.

Cheers,

Pikey.

[Zzinged]

So the bottom line is... use 95 benzine because the sticker tells you to. Only use 91 if there is absolutely no 95 available within range of the fuel you have left (usually happens outside of Bangkok).

[BSJ]

Generally, for normal 4-stroke engines 91 octane can be used if the compression ratio is less than 9 to 1, for those over 9 to 1 up to 12 to 1 use 95 octane and for those above 12 to 1 you should us 98 octane or higher. Of course the only fuel above 98 maybe Avgas and it maybe hard to buy unless you have an airport connection that can supply it in 205 litre drums. Here in Oz, years ago, the local fuel agent would drop it off with the regular fuel delivery at our farm, but not any more. Now you need to get a permit to buy it!

[keemapoot]

It's a sad state of affairs when vpower from Shell is the only dam_n thing you can run in high performance cars.

No Shell station. No luck.

Also, many older cars only run on 95 Benzene.

[SeanMoran]

Autolube will have stuff-all effect on the octane rating as it relates to oil being automatically injected into the fuel/air mix.

Firstly, sorry for the double-post earlier. Something went wrong with my wi-fi just at a critical moment I guess, and when I returned after a walk outside, it sent the same thing that it HAD sent but hadn't rendered. Rare and hopefully not to happen again, but will try to edit anything like that out if I see it again.

Regarding the oil added to the fuel/air mixture, that is exactly why the possibility of predetonation is reduced; ie. the octane rating raised by the inclusion of that autolube. By the same token, 2-strokes are such relatively low-compression engines that it's all theoretical really. It's not going to predetonate in a 2-stroke no matter what goes through the reed valve.

Lastly, that point about the better running with 91 in the Toyota has got me thinking about my 2-stroke 125 Honda which does seem prone to missing when I hammer it in second or third gear, and I've been using the 95 octane just to show here that I care.

Next tank I might try the 91 just to see if it helps the 2-stroke to keep on firing when the revs are sky-rocketing, and knowing that there's basically no chance of her knocking, being a tuey ... if I remember the theory rightly. Maybe it's the high octane fuel that's not getting through the main jet as quick as I'd like it to?

[BigBikeBKK]

Just carry a small bottle of octane booster and don't worry about it. A capful added to a tank of 91 and you're good to go.

[lennya12threh]

Thanks for the insight guys and good idea BigBikeBKK

[lennya12threh]

I double checked. It actually says 91 or higher in the manual, but I swear I saw a sticker on it saying 95. I'll have to double check when I go outside....

[Zzinged]

I ran 700hp motors trying 95,98,115 octane gas, no difference in performance, the higher octane was just insurance against engine damage.

I think you meant to say that there was no difference in performance from changing the fuel itself, but running higher octane fuel allows you to run higher compression which in turn helps produce more power. If you were pushing big power figures you ought to know that

[gosompoi]

Some stations 95 is cheaper than 91 and I have noticed some 91 is cheaper than 95. In general it should not matter but in principle 95 is better because it has a longer burn time.

[nikster]

Someone mentioned using the octane closest to what the manufacturers owner manual says and I'd agree. There is no point in putting 95 in an engine designed to run on 91. You won't get anymore power out of the higher octane. In fact in a lot of cases, you will get less because the engine will have a lower compression ratio and will not squeeze the mix enough to ensure a full burn.

That aligns with my own experience. I once had an old Mercedes E190 in Germany - great car, 10 years old at the time and never any problems. The engine spec was 91 octane. I put 95 in it at some point, not sure why. With 95, the car wasn't running nearly as smooth, and had lots of weird engine noises, as well as trouble starting. It was quite dramatic. Went back to 91 after that and all was fine again. I never knew why though as I had always thought putting in a higher octane rating gasoline can't hurt anything. Which is apparently not true.

Clearly if your engine specs say 95 you better make sure you're using 95 or you could seriously damage your engine. That much we learned in driving license school.

[katabeachbum]

Someone mentioned using the octane closest to what the manufacturers owner manual says and I'd agree. There is no point in putting 95 in an engine designed to run on 91. You won't get anymore power out of the higher octane. In fact in a lot of cases, you will get less because the engine will have a lower compression ratio and will not squeeze the mix enough to ensure a full burn.

That aligns with my own experience. I once had an old Mercedes E190 in Germany - great car, 10 years old at the time and never any problems. The engine spec was 91 octane. I put 95 in it at some point, not sure why. With 95, the car wasn't running nearly as smooth, and had lots of weird engine noises, as well as trouble starting. It was quite dramatic. Went back to 91 after that and all was fine again. I never knew why though as I had always thought putting in a higher octane rating gasoline can't hurt anything. Which is apparently not true.

Clearly if your engine specs say 95 you better make sure you're using 95 or you could seriously damage your engine. That much we learned in driving license school.

perhaps the 91 was leaded and 95 unleaded?

[katabeachbum]

Some stations 95 is cheaper than 91 and I have noticed some 91 is cheaper than 95. In general it should not matter but in principle 95 is better because it has a longer burn time.

oh, oh be careful

95 benzene is always more expensive than 91 benzene. what you have seen less expensive is 95 gasohol, also called E10 if 10 % ethanol or E20 if 20 percent ethanol. or very inexpensive as 95 E85, thats 85% ethanol. hurt most engines and fuelsystem even on cars or bikes as new as 3 years.