Few more questions

[johninspain]

i know, !!!! lol

Just thorght as i mainly do m way driving....................................

[PetrolDave]

95 usually has a higher sulphur content, this poisons the pre-cats faster. The ECU detects this and takes the engine out of lean burn and modifies the timing and increases the fuelling to increase the exhaust temperatures and clean out the pre-cat.

Since this happens more often with 95 than 98/99 this is why fuel economy with 95 is worse (I agree with the 10% figure) to an extent that using 95 fuel actually costs MORE per mile than using 98/99.

For the last few months I've been using Sainsbury's super unleaded, which is 98 octane, since it's usually only 2p per litre more than their 95 (as opposed to 7p or more at Shell and Tesco). Haven't noticed any significant change (loss) in performance, but it's a lot less painful at the checkout!

Here's what the 2006 RS4 hardback brochure says about fuel octane:

We recommend the use of SuperPlus unleaded, 98 RON. In emergencies use Normal unleaded, minimum 91 RON. Performance and consumption values were calculated using SuperPlus unleaded (98 RON).

[P_G]

Is Sainsbury's Super now 98RON? I avoided it to date as the last time I used it some 2 years ago it was 97 and the RS didn't enjoy the experience?

[sonny]

Is Sainsbury's Super now 98RON? I avoided it to date as the last time I used it some 2 years ago it was 97 and the RS didn't enjoy the experience?

Funny you should say that, when i filled my car up around 6 months ago the car did not like it too, I was convinced it was a old batch of fuel or had been mixed! it was located up in Braintree Essex, my EML even came on! I have avoided it since. however PD has been using it so it must be good.

[basilbrush]

I filled up yesterday with Sainsbury's Super Unleaded (£71) and the label on the pump states 97 RON. however im with PD here, in the sense that its cheaper than Tesco SUL and Shell VMAX by at least 4-5p per litre, and to date I have not noticed a huge difference in performance or power between 99RON and 97RON!

[PetrolDave]

The only bad load of Sainsbury's fuel I've had was at Brackley a couple of years ago, where it was labelled "Sainsbury's 98" instead of Sainsbury's Super Unleaded".

It took two tanks of Tesco 99 to get rid of the hesitancy and get the "kick in the back" back again.

[scaghead]

i use tesco 99 and have found that the best for the motor over bp ultimate and total super unleaded.... never tried shell optimax... but i defo think the opinion is dont use 95 ron as a norm...