[R4ONO]

Hi All,

I have the Julie 1.4 multiair 170bhp and generally try to use shell v power petrol where possible.

However I have recently had to use other brands of normal petrol and feel that the performance of the car is not as good. I did a bit of research and found that v power is only really for high powered engines, but I am sure it makes a difference!

Does it really matter if I use normal 95 octane petrol or 98 octane v power/super unleaded?

 

[Guest]

Hi yes it will make a slight power difference but the real benifit will be a cleaner engine and over time better MPG. I work for shell at there lub oils plant so i am bound to say it but i am sure others will back me up.

 

[KrisW]

and over time better MPG.

.. once you go back to 95 RON.

Higher octane fuels have lower energy content, so you get fewer miles per gallon than lower octane. The reason to use high-octane fuel is that they allow you to run your engine hotter (harder), because a higher octane fuel burns more slowly than regular.

You're right, though, for a different reason: Burning hotter will give you a cleaner engine because the impurities get burned off too, and high-octane fuel allows you to run the engine hotter.

 

[radosuaf]

I use the V-power, but here in Poland it's 95 RON. Did only one fuel-up with normal petrol when picking her up, so have no real comparison.

 

[timuti79]

.. once you go back to 95 RON.

Higher octane fuels have lower energy content, so you get fewer miles per gallon than lower octane. The reason to use high-octane fuel is that they allow you to run your engine hotter (harder), because a higher octane fuel burns more slowly than regular.

You're right, though, for a different reason: Burning hotter will give you a cleaner engine because the impurities get burned off too, and high-octane fuel allows you to run the engine hotter.

Hi
What i know is the opposite from readings; you will hva less egt s with a higher octane fuel. Onthe other hand, on one of the series of top gear, they tested the hp outputs of various cars and it eas proven that higher ictane gives higher hp if your car understands it. If i amnot mistaken subaru sti was getting the most difference between 95 and 98 where f.cking fiesta did had zero difference.

Fyi

 

[KrisW]

Yep, you get higher power, because the extra "octane" (it's not octane, it's fuel additives that have the same effect) means you can run the engine at a higher rpm (which also means higher temperature), but this also means higher consumption.

If you're looking to get more mpg, then use 95 RON. If you want to drive faster, use 98 or 99.

By the way, E5 Unleaded (5% ethanol) is 99 RON, and cheaper than "V-Power" - but the V-Power has other additives in it that improve combustion; it's not just "high octane".