My Octavia 1.8tsi prescribes 95/91 Ron and states the use of petrol with a higher octane number than 95 does not result in a noticeable power increase or lower fuel consumption.

Does anyone have any view on this?

would i be wasting money buying the higher octane fuel?

has anyone noticed any performance difference or felt they have saved money on mpg?

If its a turbo, it will make a difference, if n/a and not custom mapped it will make no difference but you will benefit from the cleaning additives that they put in a lot of premium fuels.

Try it and see

I bet you will likely see a decrease in fuel efficiency as higher octane petrols often have lower energy content, and compression ratio of the engine will not increase to take advantage of the higher octane rating.

I bet you will likely see a decrease in fuel efficiency as higher octane petrols often have lower energy content, and compression ratio of the engine will not increase to take advantage of the higher octane rating.

I've never heard that - it's true of LPG though as it's ±102RON but with lower calorific value.

Interestingly, there is a thread on my Elise site where one guy with a 111r (Yota n/a engine) reckons he gets 33mpg over 30mpg and a friend with a Coxster S (again n/a) reckons he saves more in better mpg running Shell V Power than with stock Shell petrol.

Sainsburys Super unleaded 97 RON is costing the same as other places Unleaded 95 RON and possibly cheaper than Shell Fuel saver.

(Obviously not cheaper than Sainsburys own 95 RON)

So why not just try 2 tanks of it?

then if you like it or see an improvement in economy allowing for any extra cost if you use others Super Unleaded,

try Shell V Power or my prefered Tesco Momentum 99 RON.

http://www.petrolprices.com

Its only money & if it costs no extra to try the 97 RON, 'whats the worst that can happen?'

& i really can not see you getting worse MPG unless you go changing something else or your driving habits.

? Is you car running as economically as it can now, Correct Tyre Pressures, No extra weight carried in the car and serviced with

good plugs and leads, clean air filter etc?

george

Edited 11 July, 201213 yr by sk4gw

I've never heard that - it's true of LPG though as it's ±102RON but with lower calorific value.

It depends on the type of the antiknock agents used to increase octane rating. MTBE and Ethanol, for instance, have lower energy density and hence decrease total energy content of the fuel.

? Is sombody mixing up Super High Octane Petrol of 102 RON for tuned engines and motorsport etc, thats is usually available at Filling Stations near Race Tracks etc & actual 'LPG' (liquid petrolium gas, which is 110 octane) ?

http://www.en.wikipe...i/Octane_rating

I ran a 4.6 V8 for several years & it was an engine built to run only on LPG (liquid petrolium gas) , the timing was advanced by 18 degrees,

Started on LPG at temps as low as -15 degrees celcius without any need for choke and did not require petrol,

there was no Petrol tank which ment i did not need a Tacho to use for towing commercially.

Needed double batteries tho with 20w/50 oil in it to get it to turn over fast enough to fire at low temperatures.

i used what was cheapest for me which was Asdas LPG and it was '110 octane'.

Morgans, Cobras, even trikes and others are racing using LPG V8's due to the higher octane and being able to run 'Lower Temps' not higher as usually believed,

and they fact you can carry a lighter fuel load .

http://www.v8engines.com

george

Edited 11 July, 201213 yr by sk4gw

No - I'd just mentiones that I knew calorific value of LPG was lower and therefore mpg is lower - about 15% lower on my BRC system although the turbo boosted harder.

The likes of VPower can improve mpg but as others have said, best to suck it and see. It can also reduce engine knock - ask Dave at Emerald why as I have no idea!

I know the OP is not LPG, but since you raised it,

As far as running the LPG when your engine is not be best suited to it or set to run at its most efficient, (eg Dual fuel)

its the fact that a litre is '63' pence compared to when you are running that engine on petrol & that today might be £1.25 a litre.

So 4.456 litres of petrol (gallon) @ £5.70 taking you 40 miles.

or 7 litres of LPG @ £4.41 taking you 40 miles is a saving

even needing around double the LPG would cost the same £5.70

If your engine is suitable and you get better performance for only a 15% poorer MPG.

34 mpg instead of 40 mpg, then thats great at 63 pence or even 80 pence a litre.

Re

'using higher octane' petrol, even in pretty low tune cars or some like old Corsa automatics where a knock sensor would put it into 'Limp' mode,

it was 'pinking' that you most felt when using supermarket fuels in the 90's,

UK 95 RON 'minimum' (UK refineries & Winter time Nov-Mar from Scottish ones)

is pretty good compared to some European fuels impoted cheaply at high demand times, and in the South thats what you sometimes get in your filling stations quite often.

95/(91) means it will run on a lower octane if needs must.

a vRS will show 98/(95)

george

Edited 11 July, 201213 yr by sk4gw

Sainsburys Super unleaded 97 RON is costing the same as other places Unleaded 95 RON and possibly cheaper than Shell Fuel saver.

(Obviously not cheaper than Sainsburys own 95 RON)

So why not just try 2 tanks of it?

then if you like it or see an improvement in economy allowing for any extra cost if you use others Super Unleaded,

try Shell V Power or my prefered Tesco Momentum 99 RON.

http://www.petrolprices.com

Its only money & if it costs no extra to try the 97 RON, 'whats the worst that can happen?'

& i really can not see you getting worse MPG unless you go changing something else or your driving habits.

? Is you car running as economically as it can now, Correct Tyre Pressures, No extra weight carried in the car and serviced with

good plugs and leads, clean air filter etc?

george

As quoted George i will try a few tanks full to see, Sainsburys sounds good, car is running grt at the moment yet i am just running it in, just done over 600 miles so i can tow this weekend, i have tyres @ correct pressure and car is unladen, hoping everything is clean and new so hadn't checked them over.

Try it and see

LOL that's what i was thinking of doing,

Stupid me had no idea that it was a new car.

(forgot your first posts at 25 miles, doh)

No way to compare then if it improves as i doubt you are even a tenth of the way to getting your best Economy with the car,

personally i might have stuck with the 95 ron and seen how it was, then changed to 97 ron next time.

I would have been interested to see how the economy was with the van on..

A small point before towing, is that 600 miles is not a great amount off miles to have done to run your brakes in.

Any coating should now be off your discs and the pads scrubbed well enough.

Just dont rush things and get the feel of it well enough, it should be a good tow car.

Enjoy yourselves & have fun.

george

Stupid me had no idea that it was a new car.

(forgot your first posts at 25 miles, doh)

No way to compare then if it improves as i doubt you are even a tenth of the way to getting your best Economy with the car,

personally i might have stuck with the 95 ron and seen how it was, then changed to 97 ron next time.

I would have been interested to see how the economy was with the van on..

A small point before towing, is that 600 miles is not a great amount off miles to have done to run your brakes in.

Any coating should now be off your discs and the pads scrubbed well enough.

Just dont rush things and get the feel of it well enough, it should be a good tow car.

Enjoy yourselves & have fun.

george

Thanks for your help and advise, will take our time and will try letting you know how the economy goes

It depends on the type of the antiknock agents used to increase octane rating. MTBE and Ethanol, for instance, have lower energy density and hence decrease total energy content of the fuel.

MTBE is also very very nasty stuff, far worse IMHO than lead.

As quoted George i will try a few tanks full to see, Sainsburys sounds good, car is running grt at the moment yet i am just running it in, just done over 600 miles so i can tow this weekend, i have tyres @ correct pressure and car is unladen, hoping everything is clean and new so hadn't checked them over.

I'd probably give the car a few firm slows from about 70mph to 10mph on an empty DC (taking care when doing so) and then driving a bit to allow it all to cool down.

There's nothing worse than brakes that are just bedded in and can stop the car, but not a car + an un-braked trailer

Edited 12 July, 201213 yr by cheezemonkhai

Great advice.

Just as well the caravan will be over 750 KG & Braked, with a maximum National speed limit of 50 or 60 mph.

george

Great advice.

Just as well the caravan will be over 750 KG & Braked, with a maximum National speed limit of 50 or 60 mph.

george

Obviously (just to be entirely clear) the above suggestion of bedding in brakes, was to be done with the car alone and nothing in tow.

Obviously (just to be entirely clear) the above suggestion of bedding in brakes, was to be done with the car alone and nothing in tow.

Will make sure i do, Many thanks for your help

Thanks for your help and advise, will take our time and will try letting you know how the economy goes

Thanks for all your advice George, i am currently running on Sainsburys 95 ron, the towing went better than expected, pulled like a train to towing speed and then i just followed the HGV's about 56 mph, my few years of towing have been done with my old XC90 so have no comparison with another car, the Skoda did feel as though its not the most stable car around 56-60 mph but no problems (felt as though the wind was blowing it at times) driving to Lytham i got around 28mph, then around 26 driving home to Warrington.

My only slight issue was reversing the car up the drive (which takes a little time) im sure i could smell the clutch overheating but am not sure.

http://www.greenergy.com/News/press_archive/2008/Largest_independent_oil_company_in_Scotland..pdf

I wondered where 'Tesco Momentum' was refined, produced or travelled from, & came upon this while trying to find the answer.

george