With my new Octavia vRS mark II almost ready (much like the equally anticipated new series of Green Wing ) I was just wondered what people's thoughts were on the use of Super Unleaded (97 RON) fuel?

Yes, Super Unleaded fuel costs more but what benefits will I get should I choose to use it from time to time? Does it only improve performance and if so how would this be evident - acceleration, throttle response, engine control?

Are there any recommendations on how much 97 RON fuel can be used instead of 95 RON? Should I limit how often I use Super Unleaded and will it have any adverse affects on the engine's lifespan or wear and tear?

I only use Shell Optimax which is 98 Ron. You may notice a slight drop in performance if you use 95 Ron Unleaded but shouldn't cause any adverse effect on the engine. Just as a footnote, on the inside of the filler cap it does mention that you should use 97/98 Ron fuel. Hope this helps.

imho, i would use the 97 ron petrol all the time in your new vrs at 5p a litre more for 97 ron thats

My remapped Mk 1 vRS is normally fed Tesco 97 RON. I can notice a difference if I run it on 95 RON.

We can only get 95 over here, funny though when I was picking the car up the sales woman mentioned the sticker inside the fuel cap, I told her it was impossible to get 97... I then said I suppose its got a full tank of 97 so ? :rofl:

I agree with the 97 users [can't get 98 round here so far]. Can't vouch for the turbo version but the 2.0FSI is much nicer on 97 and the difference here is only about 3p. They do say you get more mpg so it offsets the cost a bit. Maybe it depends on the mileage you do?

Someone on a previous thread said the engines coke up more on 95.

anyone read the report in EVO mag about unleaded fuel's????. Went to the BRC LIVE at mallory park 19th march, BP ultimate or Tesco 99 octane are the Best.

All the BRC GPN cars using Tesco 99 as a control Fuel this season as tesco are new BRC SPONSERS.

I found specification sheets recently for Greenergy 99 octane petrol (ie Tesco 99RON) and Shell Optimax. The former contains 5% ethanol including bioethanol. The latter is guaranteed 98RON but is typically 98.6RON. The spec sheets can be downloaded in .pdf format via the following links:

http://www.greenergy.com/products/technical_product_info/product_specs/99_octane.pdf

http://www.imeche.org.uk/formulastudent/pdf/Optimax.pdf

I would be interested to see a spec sheet for BP Ultimate for comparison but I haven't been able to track one down as yet.

Thanks guys. The Octavia brochure only mentions 95 RON but that may be for the other models and not the vRS. I haven't looked inside the fuel cap but that's a good point.

The new 99 RON fuel that Tesco is supplying comes from Greenergy but since higher RON does not imply better performance it's unlikely to be more than a psychological benefit. Take a look at the information here - http://www.petrolprices.com/tesco.html

In addition, I did some of my own research and whilst it is probably true that the vRS will benefit from 97 RON, most cars do not. If the engine is optimised to run better with this fuel then all well and good but it should cope with both 95 and 97/98 RON. Whether the fuel economy changes will need to be seen.

I found the following really useful sources of information -

http://www.petrolprices.com/about-fuel.html

Sections 6.13 onwards of,

http://www.faqs.org/faqs/autos/gasoline-faq/part3/

Can anyone confirm whether it's still ok to use 95 RON Unleaded occassionally? I think I will stick to the 97/98 RON super unleaded fuels but this may not always be possible.

Thanks again.

anyone read the report in EVO mag about unleaded fuel's????. Went to the BRC LIVE at mallory park 19th march' date=' BP ultimate or Tesco 99 octane are the Best.

All the BRC GPN cars using Tesco 99 as a control Fuel this season as tesco are new BRC SPONSERS.[/quote']

Well thats not strictly true.

Greenergy are producing a "Tesco 99 Motorsport" fuel - I believe its octane rating is 101.5 (to correspond with and maximise the performance to the FIA fuel specification) and is only available from Greenergy direct. Normal 99 spec Tesco fuel isnt a high enough quality and consistancy to map a high spec Turbo or S1600 engine to. Mind you at

I'm sure that I read in the owners manual that anything other than 95 would cause damage to the Cat..........will re-read when I get home....or can anyone else confirm either way?

Lance

Dont know about the mk2 but my mk1 vrs was run exclusivly on 95ron and was remapped by jabba with 95ron fuel and was running around 220BHP.My brother who now owns the car is trying some 99ron tesco fuel to see if it really makes a difference.

All FSI engined Skodas should be run on 98 ron fuel rather that 95 if possible. Its required for direct fuel injection.

As it happens the FSi turbo as fitted ot the vRS isnt as FSi as the normally aspriated version. It doesnt have the FSi mode and is just a direct injection petrol.

As it happens the FSi turbo as fitted ot the vRS isnt as FSi as the normally aspriated version. It doesnt have the FSi mode and is just a direct injection petrol.

Call me thick, but I don't understand that statement.... can you explain further please :confused:

The non turbo FSi engine runs in 2 different modes, stratified and non stratified - basically leaner running under certain conditions -- and if not used with the correct fuel can lead to allsorts of problems - coking up etc.

The 2.0FSi Turbo engine found in the vRS is "FSi Technology" or in English - the VAG way of saying direct injection - they've done away with the more complicated part of FSi - which isnt suitable for turbocharging , and will therefore mean our cars should be more reliable.

I believe the FSI mode [on say a 2.0FSI non turbo] operates at lower revs, up to about 3000 I think - squirts fuel directly into a special little chamber on the piston. Very economical. At higher revs the injection is as per normal fuel injection. It seems, according to Lummox' post, that the vRS engine doesn't have the low rev FSI type of injection, only the normal type. So it might be less economical even apart from the higher power factor.

Its more to do with the design and operation of the inlet manifold and how it delivers the air into the cylinder, piston design is also important as you mentioned.

The non turbo FSi engine runs in 2 different modes' date=' stratified and non stratified - basically leaner running under certain conditions -- and if not used with the correct fuel can lead to allsorts of problems - coking up etc.

The 2.0FSi Turbo engine found in the vRS is "FSi Technology" or in English - the VAG way of saying direct injection - they've done away with the more complicated part of FSi - which isnt suitable for turbocharging , and will therefore mean our cars should be more reliable.[/quote']

Thanks, you learn something new here almost every day .

The non turbo FSi engine runs in 2 different modes' date=' stratified and non stratified - basically leaner running under certain conditions -- and if not used with the correct fuel can lead to allsorts of problems - coking up etc.

[/quote']

Due to the lack of 97 over here it's looking like mine will be getting coked up :(

Im sure it will be just fine Gaff, all you may find is it not quite putting out 'book' power on 95. But you would prolly find they are over 200bhp anyhow.

All FSI engined Skodas should be run on 98 ron fuel rather that 95 if possible. Its required for direct fuel injection.

As it happens the FSi turbo as fitted ot the vRS isnt as FSi as the normally aspriated version. It doesnt have the FSi mode and is just a direct injection petrol.

I have an FSI Octavia 1.6 - not a VRS - but given what Lummox says, I should be using superunleaded.. What's the implication of using bog standard unleaded?:confused:

My 2.0 fsi sport shows 98 ron inside the fuel cap...with 97 in lickle tiny writing...

I run optimax, though with the car running badly at the moment don't see any improved performance, though I'm sure there must be.

Tried the tesco 99 octane and seemed a little better on that.

The non turbo FSi engine runs in 2 different modes' date=' stratified and non stratified - basically leaner running under certain conditions -- and if not used with the correct fuel can lead to allsorts of problems - coking up etc.

The 2.0FSi Turbo engine found in the vRS is "FSi Technology" or in English - the VAG way of saying direct injection - they've done away with the more complicated part of FSi - which isnt suitable for turbocharging , and will therefore mean our cars should be more reliable.[/quote']

was thinking about starting a thread like this, as this was one of my little concerns!!

i suppose there could be problems with turbo charging a proper FSi engine (compression ratios etc), maybe i talking rubbish!!

i dont think there would be a major benifit to using a fuel with a RON rated higher than the manufacturer has set. i believe the engines will adjust the timing to bring the combustion back in line with what the manufactuer has set.

that said though, they may run smoother.......will test this when my vRS comes.....

Thanks to all of you who have responded to my intial question and the resultant discussion.

I have done a bit more checking around and as someone has already mentioned, the new vRS recommends 98 (or 97) RON fuel on the fuel cap. I recall from a test on Fifth gear that the Golf GTi (mark 5) also benefited from the higher octane fuel by a few bhp and I expect it is what the engine is optimised for - http://fifthgear.five.tv/jsp/5gmain.jsp?lnk=601&featureid=143&pageid=274

My dealer says that there will be no problems with using 95 RON in the car but the best performance and efficiency will come from 97/98 RON Super Unleaded. Anything more is not worth it.

With regards to the 'special' unleaded fuels, Shell Optimax seems to come out as the best but only with high performance and tuned engines. Whether the additional expense justifies this improvement is another matter.

Personally, I wouldn't use 98 during the winter months unless;

1) You drive hard and will notice the power benefits.

2) You drive in traffic where your under bonnet temps get hot.

In the summer it should be used as a matter of course as the ignition will definately be more det limited.