I'm sure I've read some discussions on OOf about different petrol brands and qualities, but I haven't managed to locate any of them using the search facility.

I've always thought there was no noticeable difference between any brand of petrol when put into a V6.  And, according to the manual, regular grade (95 octane) is what you are supposed to fill up with.

A couple of months back, due to a special offer from Airmiles, combined with an unusual (for me) driving schedule, I was tempted to fill up with Shell V-power petrol.  I immediately noticed a dfference in the way the car behaved.  Quieter, more power and, amazingly, far better fuel consumption, especially on short journeys.

Two possible explanations occur to me:

• I am delusional
• the engine management system hasn't been working - ever

The economics are marginal - at 7p per litre more than regular, the improved mpg probably isn't enough to justify a permanent change.

Anyone got any observations?  Or can you point me to a previous discussion on this topic?

I find that the additional MPG benefits are cancelled out due to the extra power making me plant the right foot more often

Desperate Den wrote on 09. Nov 2009 at 12:08:


What's the problem, Zulu? Can't see any posts about it in the Help section!

jereboam wrote on 09. Nov 2009 at 11:18:

I have a friend with a Volvo V70 (high pressure turbo) and he reckons the better juice more than pays for itself when he's blatting up the M1.

Not a V6, not an Omega but has 4 wheels and goes like stink.

I've noticed a small but significant increase in mpg using Shell ordinary, but can't justify the extra mileage to the only garage in our area supplying it and only do if i'm going in that general direction

I am not sure about the shell stuff but  I put some of the BP ???? stuff in mine and the car did seem to run so much better 

As has been said before, whether higher octane petrol makes any difference depends entirely on your engine.

A high compression or turbocharged engine will almost certainly need high octane fuel to avoid going into knock retard and reducing power. So of course every Subaru driver will tell you it's fantastic.

On decent 95 RON petrol, most Omegas probably don't knock, and therefore there is little benefit in going higher octane. The 10.7:1 engines are probably quite close on 95 RON, though.

Higher octane fuel often contains a greater proportion of additives, and sometimes Ethanol, so often has a lower calorific value, which undoes any gain in power unless it's substantial.

Kevin

i did a test not so long back i reset the trip computer to zero  put 20 quid in of normal petrol from tesco set cruise to 60  went as far as i could round york ring road till it had o miles left  then tried that 99 octain stuff from the same tesco did same again to see if there was any difference bit more power but not a lot did the same with total bp shell and jet . Total and jet came out the same as they use the same petrol and diesal  jets super unleaded  is totals exciliam as i was told by the jet garage bp was a lot better bp ultimate was even better i found the standerd shell was about the same as jet and bp standerd petrol but the v power did give lot more power but less mpg (but lots of fun when i put it my suzuki 600 bandit front wheel dont wanna stay down)   the bp ultimate came out on top more mpg and litte more power but not as much as v power hope this helps