Difference: 91 & 95 Petrol

95 = 91 + additives which increases octane value (methane, lead, etc)

kom340 wrote:

95 = 91 + additives which increases octane value (methane, lead, etc)

Thanks, so 91 has less lead in the formula?
My car user manual says to avoid leaded fuel hence the question.

Both 91 and 95 are unleaded  in Saudi Arabia .

All cars will run on 95, but not all cars will run on 91.

For the car to run on 91 the cylinders need to be thicker (if this the right way to say it) so if your car cylinder can take the 91, then the manufacturer will state it clearly on the car manual ( In general small cars can take 91 and bigger ones 95

ahmadaq wrote:

Both 91 and 95 are unleaded  in Saudi Arabia .

All cars will run on 95, but not all cars will run on 91.

For the car to run on 91 the cylinders need to be thicker (if this the right way to say it) so if your car cylinder can take the 91, then the manufacturer will state it clearly on the car manual ( In general small cars can take 91 and bigger ones 95

Thanks.

The manual says 91 and above..
So that means both should do the job?

yes

The common assumption that 95 would provide extra power (or mileage) is wrong. Also car size doesn't really matter; it's the engine design. Just stick to what the user manual recommends.

Some people use 95 just because it's a little expensive (and so assumed better). That's also a wrong assumption.

My 3 tonns SUV has a sticker inside the fuel tank lid that says "91 recommended".

More info here: http://www.businessinsider.com/what-is- … gas-2012-9

thanks guys!

really aprreciate prompt help.

I am unable to find information

Just curious, where did you look?

Higher octane number fuel can withstand more compression before detonating.  In general, fuels with a higher octane rating are used in high-compression engines that generally have higher performance.
However, burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many high-performance engines are designed to operate with a high maximum compression, and thus demand fuels of higher octane.

Ok, to cut it short-

Some cars have a higher compression ratio than others. So higher the compression ratio, the higher octane fuel will be required and if not used it will create the knocking of the engine !

saimans wrote:

Higher octane number fuel can withstand more compression before detonating.  In general, fuels with a higher octane rating are used in high-compression engines that generally have higher performance.
However, burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many high-performance engines are designed to operate with a high maximum compression, and thus demand fuels of higher octane.

Ok, to cut it short-

Some cars have a higher compression ratio than others. So higher the compression ratio, the higher octane fuel will be required and if not used it will create the knocking of the engine !

Someone from petrochemical industry spoke out

saimans wrote:

Higher octane number fuel can withstand more compression before detonating.  In general, fuels with a higher octane rating are used in high-compression engines that generally have higher performance.
However, burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many high-performance engines are designed to operate with a high maximum compression, and thus demand fuels of higher octane.

Ok, to cut it short-

Some cars have a higher compression ratio than others. So higher the compression ratio, the higher octane fuel will be required and if not used it will create the knocking of the engine !

Thanks!

saimans wrote:

Higher octane number fuel can withstand more compression before detonating.  In general, fuels with a higher octane rating are used in high-compression engines that generally have higher performance.
However, burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many high-performance engines are designed to operate with a high maximum compression, and thus demand fuels of higher octane.

Ok, to cut it short-

Some cars have a higher compression ratio than others. So higher the compression ratio, the higher octane fuel will be required and if not used it will create the knocking of the engine !

Like a Boss ;>

Wow @saimans answered like a bawse indeed!

I am still wondering why there are only 91 and 95 here in KSA, whereas in Malaysia the variants are 95 and 97. Especially when there are a lot more lean, mean, revving machines on the road here in KSA compared to Malaysia. Any idea why @saimans?

For those of you interested:

http://en.wikipedia.org/wiki/Octane_rat … variations

Many countries seem to have 97/98 RON available, and a few also have 99/100 RON available, aside from the 95 RON.  UK even has 102 RON!  It is indeed quite strange that the Gulf countries have 95 RON as the highest octane fuel, considering the concentration of very high performing cars on the roads here.

And those of you from the US or Canada, note that an octane rating here does not correspond to the same value back in the US.  The US uses AKI (Anti-Knock Index), unlike most of the rest of the world, which uses RON (Research Octane Number).  Read the article to see how they are calculated.  The AKI rating is 4-5 points lower than the corresponding RON value.  91 RON (as here in Saudi) approximately corresponds to the 85 AKI gas available in the US, and 95 RON here corresponds to the 91 AKI pump fuel in the US.

@ sh3hryar!

It has a detailed chemistry involved but as a single line advice "Always go for 95"

presidconsult wrote:

@ sh3hryar!

It has a detailed chemistry involved but as a single line advice "Always go for 95"

Sorry, as most "always do this" or "never do this" advices, it is false, and can lead to wastage of money.

If you are driving a Camry, for example, there is no need to get 95 RON.  Your car manual will list the recommended fuel to get for your car.  95 RON is required by high-performance engines.

NOTE: "High-performance engine" does not necessarily mean large engine, and it does not necessarily exclude small engines.

modjo wrote:

Wow @saimans answered like a bawse indeed!

I am still wondering why there are only 91 and 95 here in KSA, whereas in Malaysia the variants are 95 and 97. Especially when there are a lot more lean, mean, revving machines on the road here in KSA compared to Malaysia. Any idea why @saimans?

This is all the game of Chemistry, here it goes...

Finished petrol product must meet certain octane number specifications. Thus refineries control this parameter during production and must certify that a gasoline meets specification (as per the requirement, so different for different countries) before it is released. Other important technological properties of the commercial gasoline ASTM distillation points, flash point, aromatic and sulfur content etc. Therefore, there is a set of fixed process well defined in the refineries to produce a type octane fuels as per the demand. And any changes to get a different grade of blended fuel from the refinery will require a lot of investment (money) to get the process changed, which by any means is not an easy task.

Hope it clarifies. BTW, higher octane number doesn't mean the good quality of the gas. It just means different type of blending of iso-octane and heptane.

@saimans, if you were trying to explain what the ratings mean, you did not explain what "octane number" means, which is the crux of the matter, and which is where chemistry is involved.  I doubt anybody here, save a member or two, knows what "octane number" means.  Yes, it is some specification of the fuel, as you stated, but what exactly is octane rating/number?  And before that, what is octane?

For those interested, I already posted the Wikipedia link which explains it in more than enough detail for a layperson.

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

Trapezius wrote:

@saimans, if you were trying to explain what the ratings mean, you did not explain what "octane number" means, which is the crux of the matter, and which is where chemistry is involved.  I doubt anybody here, save a member or two, knows what "octane number" means.  Yes, it is some specification of the fuel, as you stated, but what exactly is octane rating/number?  And before that, what is octane?

For those interested, I already posted the Wikipedia link which explains it in more than enough detail for a layperson.

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

Octane Number is the numerical representation of the ability of a fuel to resist knocking when ignited in the cylinder of an IC engine. In Broad terms Blending of 95% of Iso-octane (Having ON of 100) with 5% of heptane (Having ON of 0%), will give 95% ON fuel. Any fuel knocking at the same compression ratio as this mixture is said to have an ON of 95.

Rest all is explained in the link you have provided !

I don'n know much about chemistry, if some expert cat tell me about my Camry car 2005. which petrol should I use 91 or 95 in ksa?

91 is totally fine for that, even if you had a 2014 Camry!

Can anyone tell me which petrol i should use for Honda Civic 1.8 Litre engine.  Pervious owner was using 95 but if 91 is good enough then can i use 91 even if i was running on 95 uptill now ?

See the 2 posts directly above yours!

Which type out of 91 and 95 I should use for Cheverlat Malibu 2011?

For Chevrolet Aveo what should I use in KSA 91 or 95 ???

91 is enough for all economy cars and also non-high performance mid-size cars.  95 is for BMWs and the like (European cars, high performance cars), or for 6 (and above) cylinder Japanese cars (but even 6-cylinder Jap cars will be fine on 91).

I bought used car before the guy was using 95 is it ok to change to 91 ?

Yes, he was just wasting his money, you don't have to!  You can use 91 regardless of what the previous owner was using, it is after all, still a car with a tiny engine.

Dear thank you very much for your response .

Really appreciate .

Best Regards
Fahad

You are a welcome!  Just as a relevant story, I was using 95 in my RAV4 for 2 years until a friend told me that I was wasting my money.  I switched to 91, and that dropped the fuel economy -- and thus the range -- of the car.  However, the difference in price between 95 and 91 was greater than the drop in fuel economy, so I still ended up saving money overall after switching to 91.  I sold it after another 2 years, and in those 2 years I saved a few hundred Riyals because I used 91 instead of 95.

Ahan (y)

Assalamu Alaikum

Your answers were nice reg petrol 95 & 91.

My car is Cheverlet Lumina LS 2004 model with 6 cylinders. My previous owner used 95 and till now I used 95 only.

Since 95 rate is toomuch now. Can I change from 95 to 91? If yes, I just have to fill 91 (like I do topup - when my petrol says approx 15% only available.

Appreciate your time in order to reply me.

In my case our company used to pay for gasoline & we fill 95. Our office stopped paying for gasoline & we have to fill our self. When I switched to 91 , I brought tank level to minimum possible level and filled with 91 . It is working fine
My car is Caprice 2005 model