2.8 V6 - Optimax or Standard Unleaded ? Which one.

[Hudson]

I have a 1999 A6 2.8 Quattro Tip, i currently just use 95 RON unleaded, will i notice if i started to use 98 RON ie Optimax ? I can see that the 4.2 V8 may see an improvement but would my V6. I was thinking of more accelaration and mid range torque. I not that either top gear or the other one did a test using 95/98 RON and except for an Impreza i don't think it made much of a change.

[scooby_simon]

Run my Impreza on Optimax and I could see a small difference.

Just had an ECU reset and it's made am even bigger difference (old car)

We also had a A4 with a 2.8V6 which we also ran on Optimax only and we also think it made a difference too.

Not as much mind.

Optimax appears to make a bigger difference in Turbo cars. We are even running wifee's V70 on Oppie...

[Edd_W]

Almost any car with knock sensors will benefit from a slightly higher octane fuel because it will allow a little bit more ignition advance before the combustion start to go out of control - pre-ignition & pinking.

You may see a small MPG improvement as well depending on driving style, it is possioble that this improvement is enough to compensate for the higher cost. I would not bother with Optimax though, just any super UL will do. Sainsbury's sell their for only about 1ppl above normal UL.

[Soundwave]

My A6 4.2Q definitely runs better on higher octane fuel. It actually seems to run better on the Tesco super-unleaded than anything else, it may be the octane rating of 99 which my engine seems to love, and because its Tesco, it doesn't cost that much more - in fact i recently paid 90.9 ppl for 99 octane fuel at Tesco.

Further, on the inside of the fuel filler flap, it has got 98/95RON where the 98 comes first and is in a large sized font and then the 95 bit is smaller, suggesting that Audi want you to run it on 98 or above RON. Maybe, have a look for this on your car.

HTH.

[Soundwave]

Actually, i've just remembered that there was a group test on performance petrol vs standard petrol done just last week on 'Fifth gear' using different engines (cars). The outcome was very interesting and can be viewed at the following link: http://fifthgear.five.tv/jsp/5gmain.jsp?...ature%20stories

[Hudson]

Cheers for all that, would i be best to ''drain'' ie use, all the unleaded first before i fill up with super or could i just keep mixing it in ??

[Soundwave]

Nah, i'd just mix it in.

If i do have to use the normal stuff, i put as little as possible in so that when i do find some good stuff, it aint diluted too much. If you have already got alot of the normal stuff in there already, then i'd use as much up as you can (go to as near to empty as you dare or are familiar with) and then fill up with the good stuff.

One more thing, never put too much fuel in at once. Weight is the real enemy when wanting to go fast and the amount of fuel you put in is no exception to this rule. I find that if i fill up my tank, the car feels really, really heavy and is alot slower, no matter which fuel i use. At the same time, i dont want to be stopping at the pumps every few miles, so what i do is put in 10.00 of 99RON and the car ruddy flies along, isn't too heavy and goes a reasonable distance before needing re-fuelling.

Just remember the last time you ran out of petrol and went to get 5 litres of fuel in your petrol-can, feels relatively heavy doesn't it? Imagine all the weight of increasing amounts..

HTH.

[Hudson]

Good tip, i must admit i do keep my car to the max every week and just fill up every Friday (ie tonight), but taking into account the weight i can see your point.