Dirty boy! Looks like the flap of an old transit!

ha ha.. well, dirty flap, dirty mind?

The wonderful thing is that if you do not want to follow the Manufacturers recommendation you just try what you want.

You know how you drive and what you want from your vehicle.

Maybe try Tesco Momentum 99 Ron, or Shell V Power, Sainsbury's Super Unleaded 97ron.

A few tanks of the same stuff on your regular run in that season,

because winter might well be different from summer.

If only that you might be going slower in winter but be warming up the car for longer and the alternator is working harder.

So test the fuel with a higher octane, then compare after doing your journeys with the lower octane or cheaper fuels

with a 95 ron minimum.

http://www.pertolprices.com

Then you will be in a position to tell us how your tests & comparisons went.

George

I've already run two tanks of regular - driving no different to normal I'm getting about 31.5 compared to about 33-ish on super, however I'm well aware that different ambient temperature, driving style/roads/other factors means this result is pretty arbitrary - hence the reason for the thread in the first place

Basically i think if you are using the tanks of fuel once the car is up to running temp and giving it some sporting driving you will feel the difference of the higher octane fuel, but not notice any improved economy with it.

*I think you might notice the down side of the lower octane after using it for a while.*

If the car just gets used in a calm manner on regular trips then comparing the cheaper stuff against the dearer stuff for economic reasons should be easy.

Jumping from one fuel to another might just show very little difference.

I go through at least a couple of tanks of fuel a week and am happy with Tesco Momentum.

Through the coldest months i will use 95 ron or 97ron, but the the driving is less spirited & on short journeys where the engine is never properly warm before stopping, i notice very little difference.

There are cars, ECU's etc where 95ron is fine and a higher octane makes not a jot of difference.

I have a Picanto & a Jimny that do not get an ounce/inch of improvement with expensive fuel in.

george

I looked at the manual and it said basically look at the sticker in the flap? Unless you're reading something different?

https://mediaportal.skoda-auto.com/resource/documentation/manuals/en/Octavia/05-2012/Manual/A5_Octavia_OwnersManual.pdf

Page 162, right hand column, second paragraph down. To me that means the stated power is achieved with 95 RON but Super 'can' not necessarily 'will' increase power or economy.

You need to read just below that for the vehicle in this thread. Still page 162 Right hand column.

'Prescribed Fuel' - Unleaded 98 (95) ron.

(Thats the relevant bit about using 95 ron if needs must!)

george

You need to read just below that for the vehicle in this thread. Still page 162 Right hand column.

'Prescribed Fuel' - Unleaded 98 (95) ron.

(Thats the relevant bit about using 95 ron if needs must!)

george

Thats the older TFSi engine I believe. The OP stated in the first post that it's a TSi he has.

Edited 12 September, 201213 yr by Metblackrat

That is 'Prescribed min 95 ron' is it not.? Not 95 ron (min 91)

so that is in your link.

"on vehicles using prescribed unleaded petrol of min 95 ron, the use of petrol with a higher octane can increase the power and reduce fuel consumption"

Back to try and see, you should know in a few weeks, and if there is no difference then why waste your own money,

or in the case of someone else paying, theirs.

'what is the worst that can happen?'

george

If you have a remap then you will not have full power on the lower Octane, mappers always say we can only map it to what fuel is in at the time and they prefer Shell optimax. In the days of 2 3 and four star petrol, if you used a lower octane to save money, they would pink ( pre ignition) going up a steep hill and would only run OK again on the flat or going down hill, I cannot see a modern ecu as being any different, apart from the fact it will adapt to the fuel you use without you knowing, they say not instantly but maybe a tankful. The 5 gear test concluded you did get more mpg for the higher octane but only cars that really were designed for the higher octane fuel . So although more initial cost about the same as you got more mpg. Athletes run on good food, not Mcdonalds , same with cars, they run better, as my Gran said, strength goes in at mouth , ( or fuel flap!

If you are pounding miles on the motorway, you may not be, then i cant see the point in going for more expensive "performance "fuel. Its not like you are sitting at max power all the time you are merely cruising. I used to kid myself that i could feel the difference in my S3 when using the super unleaded but in reality i couldnt. Its all kid-ology. Would be interesting to see two identical cars on track with the different fuels to see the diifference then the same two cars on a long run together to compare MPG. I would be very surprised if the results were any more than marginal. This would also be dependant on the state of tune of the engine. A highly tuned engine would see larger gains but i still suspect these would be negligible.

The theory is that with the bigger bang you need less rpm to achieve the same speed. In reality you are talking 10's of rpms saved which on an engine doing 2000 rpm at cruise is miniscule. However it is less and as such can be legally quoted by the petrol companies.

I have to admit that this theory miffs me somewhat. Given that the gear ratios are fixed etc, x rpm will always = y mph. You cannot lower the rpm without lowering the speed as it's all mechanically linked. What does happen is less fuel required to achieve the same rpm. (Just like a remap)

Unfortunately I've had a bit of a disagreement with my boss who would prefer that I used regular unleaded as its cheaper.

I claim my fuel by pence per mile. The economics of mileage are then down to me. Although my boss is quite impressed with the 60+mpg I'm getting at the moment.

One wonders what people like Shark (who have the ability to do a like-for-like test on the rolling road) make of this.

Quote:- "The theory is that with the bigger bang you need less rpm to achieve the same speed. In reality you are talking 10's of rpms saved which on an engine doing 2000 rpm at cruise is miniscule. However it is less and as such can be legally quoted by the petrol companies."

>>>>>

Surely the road speed is governed mechanically, purely by the engine rpm plus whatever gear you are in. You achieve this quote you would have to alter the gear ratio for top gear or the final drive?

It says 95 MINIMUM, but also says SUPER.

I take that to mean that the car is designed to be run on (recommended) Super, but can run on any fuel that has min 95 ron. Am i right?

Ignore the words, its the RON rating, since a lot of euro countries call regular unleaded as super.

The TFSI engine has a 98 RON sticker with (95) in brackets. It also states optimum performance on 98 RON, so clearly the ignition timing and presumably valve timing can take advantage of the additional predetonation resistance and squirt a bit more in and boost a little more. Not sure how thsi translates to better economy though as the fuel does not have a higher calorifi density as far as I know.

My a**e gyro couldn't tell any difference pre DV and remap, but then it was probably making around 160 - 170 bhp max at the time. In it's current state, there is a marked difference between 95 and 99 RON, perhaps usnsurprisingly. If mine wasnt remapped, I would use 95.