95 or 93 Octane?

[Sinbad]

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...

You will get better performance IF your engine management can advance timing to make use of the extra detonation resistance of the higher octane petrol.

There is no performance difference between 50ppm and 500ppm diesel but there is a NOTABLE difference between brands of diesel for some cars.

 

[danlr]

I meant 50ppm and 5ppm as I lived in the UK where 5 ppm was available and now can only get 50ppm in SA

Might be other factors that makes a difference but honestly felt like the car is a little more sluggish here is SA - so might be something other than the Diesel. Used BP there and here

 

[Fazda]

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...

:wtf: You obviously aren't buying diesel in SA!

 

[danlr]

Fazda, used to buy 5ppm in the UK and now 50ppm in SA - same car though

 

[Naks]

Assuming you are driving a modern car with electronic injection & timing, always use the highest quality of fuel you can buy, i.e., 50ppm and 95 unleaded.

 

[Gnome]

Assuming you are driving a modern car with electronic injection & timing

As was said before, for a N/A engine 93 octane in the high veld is about the same as 95 octane in coastal areas. 90%+ of N/A cars will have no benefit @ coast with more than 95 octane and therefore no benefit @ high veld with more than 93 octane. Unless a car says it will benefit from higher than 95 octane at a coastal region, there is no point using higher than 93 octane at the high veld. I've tested this again and again in different model N/A cars. Fuel usage actually increased in many cars while running 95 octane.

However some cars are designed to take up to 100RON at coastal regions (Merceds AMG, Audi RS, BMW M series, Porhce, Ferrari ,etc.) Those cars will see real performance benefits from going 95 octane in the high veld or more than 95 octane @ the coast.

Turbo charged cars should almost always benefit from 95 Octane in the high veld.

 

[AndyC]

Driving around in my gf's 1.4i citigolf I got horrible consumption on 93 (8.5l/100km) but it improved to around 6l/100km when I used 95.

The difference was that I had to use far more throttle with 93 to get the car up to speed than with 95 in the tank.

 

[Drunkard #1]

You will get better performance IF your engine management can advance timing to make use of the extra detonation resistance of the higher octane petrol.

^ This is my feeling on the matter. Modern engines will compensate for "low" octane fuel by burning it at less than maximum efficiency, so even if the same amount of energy is contained in 1L of both fuels, the amount of useful energy released is more for higher octane fuel.

I used to put 102 octane in my bog standard Telstar (and drive like a youth); consumption as definitely better than with 93 octane. Also, the car felt a lot better at high revs (IIRC, it could rev 8000) with the racing fuel. This was on the Highveld.

Now I drive a Corolla (like an old man) and still use 95 octane, because I reckon that even that engine is smart enough to change the timing to the improve efficiency, and that the improvement is enough to offset the extra cost.