95 or 93 Octane?

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Hugo_ZA

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Hey guys,

I have always opted for 93 Octane as there was never any real difference in performance and consumption between the two whenever I tested. However, I put 95 Octane in my car (2005 Merc E320 V6) on the weekend and have noticed a considerable reduction in fuel consumption.

What are your thoughts on this, guys?
 
More down to the colder weather and less aircon being used IMHO.
 
It wont affect fuel consumption.

Higher octane fuels are only necessary for higher performance engines. Your V6 might have large enough cylinders to benefit.

A higher octane fuel has the exact same amount of energy in it, but it burns a little slower, than a lower octane fuel. That is useful in prevent pre-ignition, or knock, in your engine. Pre-ignition is when the fuel/air mixture ignites in your cylinder under pressure, instead of when the spark fires. It can be extremely damaging for your engine.
 
what Ancalagon said is correct, HOWEVER i myself have also noticed slightly better economy on 95 octane, whether it offsets the price though i am not sure.
 
Doesn't really have anything to do with engine or cylinder size. It depends exclusively on the engine, usually the compression and management system. Turbo charged engines probably benefit the most.

Your car's engine will almost certainly benefit from 95 octane. Best to double check with Mercedes however (call the service centre).

Ancalagon said:
A higher octane fuel has the exact same amount of energy in it, but it burns a little slower, than a lower octane fuel.
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Usually higher octane fuels actually have lower energy levels because of the extra chemicals added to boost the octane level.
 
Ancalagon said:
It wont affect fuel consumption.

Higher octane fuels are only necessary for higher performance engines. Your V6 might have large enough cylinders to benefit.

A higher octane fuel has the exact same amount of energy in it, but it burns a little slower, than a lower octane fuel. That is useful in prevent pre-ignition, or knock, in your engine. Pre-ignition is when the fuel/air mixture ignites in your cylinder under pressure, instead of when the spark fires. It can be extremely damaging for your engine.
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It's not cylinder size. It's compression ratio.
95% of naturally aspirated engines will be perfect on 93 octane up here. If they ping on 93 here, they'll ping on 95 at the coast.
 
Well here is a comparison. Driving from Broadacres Virgin Active to my place on Pineslopes with the aircon on in regular Sunday traffic in Fourways I would sit on 15l/100km when I stop at home. With the 95 in the exact same conditions my consumption was at 12.1l/100km.
 
Hugo_ZA said:
Well here is a comparison. Driving from Broadacres Virgin Active to my place on Pineslopes with the aircon on in regular Sunday traffic in Fourways I would sit on 15l/100km when I stop at home. With the 95 in the exact same conditions my consumption was at 12.1l/100km.
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that is a really bad and inaccurate comparison
 
If you look on the fuel cap it will tell you what type of petrol to use.

You get better consumption and performance because the engine is designed to work off that fuel.
 
D3x! said:
not just that, he should be comparing over an entire tank, not the computers on board computer reading
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Nah, for a fixed journey, the OBC trip reading should be pretty accurate.
 
D3x! said:
not just that, he should be comparing over an entire tank, not the computers on board computer reading
Click to expand...

The reason I did the comparison the way I did was because I have been driving that route every Sunday for a year. Always takes the same amount of time etc. Either way, I will do the comparison next time I fill up as well.
 
Sinbad said:
Nah, for a fixed journey, the OBC trip reading should be pretty accurate.
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not really, for example when i fill up that day it will show say 9.0l/100km but over the following days it will drop to 7.0l/100km as it has more km to average out over
 
D3x! said:
not really, for example when i fill up that day it will show say 9.0l/100km but over the following days it will drop to 7.0l/100km as it has more km to average out over
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Depends how yours works I guess. Mine resets every trip automagically... so it's always a reflection of that precise trip.
 
This whole thing is pointless without proper consumption comparisons. There are so many factors that could have affected the consumption on Sunday, that the entire discussion becomes moot.

On the Highveld, 93 is the same as 95 at the coast, so there shouldn't be any difference at all.
 
D3x! said:
not really, for example when i fill up that day it will show say 9.0l/100km but over the following days it will drop to 7.0l/100km as it has more km to average out over
Click to expand...

Not true in my case as I have two trip computers. One which measures from reset and one which measures from start. The rest gets done when I fill up and the second one I reset when I start the car (if I drive at intervals of less than 1 hour, after which it resets by itself).
 
Fazda said:
This whole thing is pointless without proper consumption comparisons. There are so many factors that could have affected the consumption on Sunday, that the entire discussion becomes moot.

On the Highveld, 93 is the same as 95 at the coast, so there shouldn't be any difference at all.
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that is pretty much what i was saying
 
Lol, either way the question was this "are certain engines simply designed for 95 octane and as such would 93 octane negatively affect the economy of said engine"?
 
With new engine management systems "they" claim the higher octane you use the better for fuel economy, engine wear and tear, performance...

I notice a difference between 50ppm and 5ppm Diesel in both performance and economy...
 
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