I did it, i accidentally put ethanol e10 fuel in my Skoda Octavia vrs. Up to now I have been religiously committed to fueling up with the recommended 95RON premium fuel and on some occasions the even more dear fuel the 100RON fuel. Today though for some reason I had a lapse of memory and instead of picking the 95 I accidentally picked the E10 and started filling up. As I'm standing there filling up I notice the pricing, which confuses me as I was pretty sure that wasn't the cost of the 95, I then realise my error. I stop the filling of the tank and I put the hose back and pick up the correct one and fill up. I endedb up filling with 17 litres of ethanol fuel and 24 of the 95. Now maybe I'm just being concerned for nothing, and maybe it's not such a major issue but seeing that the manufacturer instructs that it only has 95 I'm left wondering. I've searched online and most sources say it shouldn't be an issue as Australia's ethanol fuel is high quality and if it's a one of or rare it shouldn't affect the engine. I hope it will be OK 😬

In the UK 95RON fuel IS E10 so all the Octavia owners here who have been filling with 95RON have been filling with E10 for many years.

Even our 97/98/99RON is E5.

It will be ok Would be different if you put a tankful of E10

25 minutes ago, PetrolDave said:

In the UK 95RON fuel IS E10 so all the Octavia owners here who have been filling with 95RON have been filling with E10 for many years.

Even our 97/98/99RON is E5.

Ok thanks for clearing that up. Yeah it's interesting why here in Australia the dealer was like absolutely no e10 ethanol when I first bought it. Could it be because it's also 94RON and not 95 like the one sold in the UK. Anyway regardless I'm relieved it's not that bad and I'll just play it safe and keep on putting the 95 and 100 premium fuels

9 minutes ago, Exkiwi said:

It will be ok Would be different if you put a tankful of E10

Yeah that's true. Could have been worse imagine if i had put diesel 🤣😳😭

31 minutes ago, PetrolDave said:

Even our 97/98/99RON is E5.

Interesting I just saw this. Maybe the 5% ethanol doesn't have such a negative effect than the 10% does on the turbo engines

42 minutes ago, LuxoviaRS said:

Interesting I just saw this. Maybe the 5% ethanol doesn't have such a negative effect than the 10% does on the turbo engines

It's not the ethanol concentration it's the higher RON value that is beneficial (provided the ECU tuning has maping for the higher RON).

Like most things in Australia, there can be a little variation on available fuels and the rules governing E10 constituents depending on which state you live in.

As far as I am aware, nationally, the E10 uses our base 91 RON fuel with 10% Ethanol added which takes it to 94 RON rating.

The issue is not with the ethanol/petrol mix but the fact it is has a slightly lower RON rating (a marginal issue I suspect unless you regularly push the engine to the red line), but more so about the 91 RON fuel having a much higher sulphur allowance than 95+ RON fuels.

Not going to be much of a problem with the one-off half-tank fill you did, but not something you would want to make a regular thing.

In South Australia our E10 is not allowed to advertise the (nominal) 94RON rating because the pump has a very small sticker on it saying that the Ethanol content is "up to 10%", which means that the RON rating could actually end being anything between 91 and 94.

What confuses me more is the 100RON fuel you claim to use:

1) As far as I am aware the highest-octane fuel generally available on Australian forecourts is Premium 98RON. Yes, you can get 100 RON PULP fuel (even 110 RON) but these are racing fuels that suppliers specifically recommend NOT using in standard road going cars as it ruins the catalytic converter.

2) Even more worrying is that you may be using E85 fuels (rated at 105RON), fairly rare on petrol forecourts but can only be used on a very small range of engines and definitely NOT in a Skoda 2.0tsi engine, or any VW engine sold in Australia (unless you imported a model from Brazil).

A few years ago, the Australian National Government sort of committed to raising fuel standards to match Europe but has got bogged down with all sorts of lobby groups and it has gone pretty quiet on that front despite their more recent commitment to the NVES scheme to reduce vehicle emissions.

Coincidentally, for the first time in over 50 years of motoring, today I started accidentally putting 91 RON in my 1.4tsi Octavia (I use 91 in my other car) but realised after 3.5 litres and went and paid before putting in a further 30 litres of 95 RON.

Edited 17 August, 202517 Aug by Gerrycan

Although not linear, if you added

17 / 41 litres of 91RON and 24 / 41 litres of 95RON then ended up with about 93.3 overall

But you probably already had about (I am guessing here) 10 litres already in the tank, so overall would have been nearer 94RON (including existing and two top ups)

But fuel is sold with specs quoted as a minimum, not an average, so chances are your 91 was actually 91 and a bit, and 95 was really 95 and a bit.

As a one off I wouldn't worry, but if it really freaks you out, as soon as you have a few litres space in the tank add some high RON fuel, it will all get mixed up (and every time you go around a corner it will mix a bit as will slop around in the tank). It's not like you have accidentally stuck some diesel in there.

6 hours ago, Gerrycan said:

Like most things in Australia, there can be a little variation on available fuels and the rules governing E10 constituents depending on which state you live in.

As far as I am aware, nationally, the E10 uses our base 91 RON fuel with 10% Ethanol added which takes it to 94 RON rating.

Yes. Thanks for defining ethanol fuel and it's constitution creation part. You are correct with it being 91 and having higher sulphur content

6 hours ago, Gerrycan said:

The issue is not with the ethanol/petrol mix but the fact it is has a slightly lower RON rating (a marginal issue I suspect unless you regularly push the engine to the red line), but more so about the 91 RON fuel having a much higher sulphur allowance than 95+ RON fuels.

Not going to be much of a problem with the one-off half-tank fill you did, but not something you would want to make a regular thing.

Yep the lower RON is a slight issue i agree as it's only a one off. No i hardly redline the engine, hard to do so when you're in a very busy city with congestion and speed cameras everywhere and also coppers. Also don't want to strain the engine.

6 hours ago, Gerrycan said:

In South Australia our E10 is not allowed to advertise the (nominal) 94RON rating because the pump has a very small sticker on it saying that the Ethanol content is "up to 10%", which means that the RON rating could actually end being anything between 91 and 94.

Interesting never knew that about South Australian fuel pumps, here in Sydney they are, but thanks for explaining why they are not allowed makes sense

6 hours ago, Gerrycan said:

What confuses me more is the 100RON fuel you claim to use:

1) As far as I am aware the highest-octane fuel generally available on Australian forecourts is Premium 98RON. Yes, you can get 100 RON PULP fuel (even 110 RON) but these are racing fuels that suppliers specifically recommend NOT using in standard road going cars as it ruins the catalytic converter.

2) Even more worrying is that you may be using E85 fuels (rated at 105RON), fairly rare on petrol forecourts but can only be used on a very small range of engines and definitely NOT in a Skoda 2.0tsi engine, or any VW engine sold in Australia (unless you imported a model from Brazil).

A few years ago, the Australian National Government sort of committed to raising fuel standards to match Europe but has got bogged down with all sorts of lobby groups and it has gone pretty quiet on that front despite their more recent commitment to the NVES scheme to reduce vehicle emissions.

Coincidentally, for the first time in over 50 years of motoring, today I started accidentally putting 91 RON in my 1.4tsi Octavia (I use 91 in my other car) but realised after 3.5 litres and went and paid before putting in a further 30 litres of 95 RON.

Oh no sorry that was a mistype i meant to type 98 not 100. Not sure why it typed that. My mistake. I myself have never encountered 100 here in Australia. Thanks for explaining. No I only use 95 and 98.

6 hours ago, Gerrycan said:

A few years ago, the Australian National Government sort of committed to raising fuel standards to match Europe but has got bogged down with all sorts of lobby groups and it has gone pretty quiet on that front despite their more recent commitment to the NVES scheme to reduce vehicle emissions

Yes i has read about this move from the government improving fuel and reducing fuel. Who knows, I personally think their focus now is more on pushing net zero, BEVs, and hybrids.

7 hours ago, Gerrycan said:

Coincidentally, for the first time in over 50 years of motoring, today I started accidentally putting 91 RON in my 1.4tsi Octavia (I use 91 in my other car) but realised after 3.5 litres and went and paid before putting in a further 30 litres of 95 RON.

There you go, happens to the best of us I'm glad I'm not the only one. Good thing you picked it up with only 3L filled. I'm not sure what the recommended fuel is for the 1.4, I wouldn't think the 91 is a major issue, does it accept that rating or do you need to input a higher RON fuel?

6 hours ago, SurreyJohn said:

Although not linear, if you added

17 / 41 litres of 91RON and 24 / 41 litres of 95RON then ended up with about 93.3 overall

I guess, it makes sense. I'll take your advice given further down and as a solution i will use about half a tank then fill up with 98 to bring it closer to 95, thanks for the tip

6 hours ago, SurreyJohn said:

But you probably already had about (I am guessing here) 10 litres already in the tank, so overall would have been nearer 94RON (including existing and two top ups)

The tank is only 45 so only had 4 l left. But yes it is a mixture of 95 and 98 fuel. Not sure if that's enough to compensate though

6 hours ago, SurreyJohn said:

But fuel is sold with specs quoted as a minimum, not an average, so chances are your 91 was actually 91 and a bit, and 95 was really 95 and a bit.

Fair enough, I'm not really aware of the rules around fuel advertisement, that could be the case. Does make sense.

6 hours ago, SurreyJohn said:

As a one off I wouldn't worry, but if it really freaks you out, as soon as you have a few litres space in the tank add some high RON fuel, it will all get mixed up (and every time you go around a corner it will mix a bit as will slop around in the tank). It's not like you have accidentally stuck some diesel in there.

Yeah shouldn't be a major issue having been a one off. My mind is more at ease now with all of you here supporting, and guiding explaining. Thanks very much

Edited 17 August, 202517 Aug by LuxoviaRS

I only use e10 (Melbourne), have done for years. And I have lots of Skoda driving friends who only use 91 and have never even thought about RONs. No issues at all.

Have tried 95 for a 6 months to see if there was any change in efficiency - there was not.

Edited 18 August, 202518 Aug by astr0b0y

Australia has poor fuel and unlike the rest of the world except Trumpdom cant run E10 in VAG engines. However easiest way is read the info inside your fuel cap It says on one side 95% minimum RON and on the other it says E10. So a logical mind would realize that in AUS you use 95/98 and in the developed parts of the works you can use 95 with E10 as the RON qualifies and so does E10. Simples

1 hour ago, astr0b0y said:

I only use e10 (Melbourne), have done for years. And I have lots of Skoda driving friends who only use 91 and have never even thought about RONs. No issues at all.

Have tried 95 for a 6 months to see if there was any change in efficiency - there was not.

Interesting thanks for sharing your experience. I'm still reluctant to use e10. Would rather play it safe and use 95 and 98 though more dear.

54 minutes ago, Exkiwi said:

Australia has poor fuel and unlike the rest of the world except Trumpdom cant run E10 in VAG engines. However easiest way is read the info inside your fuel cap It says on one side 95% minimum RON and on the other it says E10. So a logical mind would realize that in AUS you use 95/98 and in the developed parts of the works you can use 95 with E10 as the RON qualifies and so does E10. Simples

True re Australian fuels. Yes on the fuel cap it has 95 and on the other side E5 and E10. Yes logically I myself will stick with the 95 and above though others probably don't see an issue with lower RON. Yes in other parts of world with more developed fuel e5 and e10 are more suitable with higher RON.

59 minutes ago, LuxoviaRS said:

As I said Read the RON then the E rating It says 95 MINIMUM and if that applies you can use E10. As there is no such thing in AUS as 95 E anything you cant use E10 fuel which is only 91 with a very small rocket up its arse. Using 91 will cause problems with pre ignition etc and will F you engine eventually. But as above there are those who obviously know better than the manufacturer and perhaps should inform VAG of their error. WHy would they put 95 MINIMUM on the fuel cap if they didnt mean it .

I asked VW a few years ago and here is their reply

Hi Graham, 

Thank you for your email. 

Volkswagen only recommend the use of 98 or 95 as minimum. We do not recommend any other type of fuel to be used, including E10.

If you have any further questions, please feel free to send me an email or contact our Volkswagen Customer Experience team on 1800 607 822. You may receive a survey shortly. This survey relates to the service and experience I have delivered to you. It does not relate to the outcome of your enquiry, dealership, your vehicle or any other external party. Only my service to you.

Good enough for me but obviously not for some. Always some isnt there

I've always used 98 in VW & Skoda, won't use anything less. Moreover, I'd never touch E10 since a previous bad experience in another car due to ethanol's moisture retention characteristics (aka fuel pump destroyer). Opinions will always be divided, but imho ethanol is just false economy.

@LuxoviaRS , it's unlikely that the amount of E10 you accidentally put in there will cause any issues, but my advice is to stick with 98 if you can and your engine will thank you.

9 minutes ago, SouthernComfort said:

I've always used 98 in VW & Skoda, won't use anything less. Moreover, I'd never touch E10 since a previous bad experience in another car due to ethanol's moisture retention characteristics (aka fuel pump destroyer). Opinions will always be divided, but imho ethanol is just false economy.

@LuxoviaRS , it's unlikely that the amount of E10 you accidentally put in there will cause any issues, but my advice is to stick with 98 if you can and your engine will thank you.

Well I tried both 95 and 98 in my Tiguan R Line and couldnt tell any difference in performance whatever. The only difference I found was that my wallet was lighter but not enough to enhance cars performance

Thanks all for your expertise knowledge and experience in this matter. I for one knowsnot to use the e10 and now understand even more why 91 RON etc I'm certainly not taking that risk purposely. I don't feel the need to solely stick to 98 @SouthernComfort though will use it on occasion as price dictates.

3 hours ago, LuxoviaRS said:

I don't feel the need to solely stick to 98 @SouthernComfort though will use it on occasion as price dictates.

Exactly what I have done with the Octavia's I've owned over the past 9 years.

As I said, opinions will remain divided. We'll all stick to our own choices. Given the frugal fuel consumption in these cars I don't care much about price, just fill up at the bottom of the silly price cycles we're subjected to in this country.

WHERE you buy your fuel from is an equally important (and likely contentious) matter, but I'll leave that one well alone!

@PetrolDave No place in the UK as sold 98 ron for over a decade.

But there is E5 97 or 99 ron minimum Super Unleaded on sale.

1 hour ago, SouthernComfort said:

As I said, opinions will remain divided. We'll all stick to our own choices. Given the frugal fuel consumption in these cars I don't care much about price, just fill up at the bottom of the silly price cycles we're subjected to in this country.

WHERE you buy your fuel from is an equally important (and likely contentious) matter, but I'll leave that one well alone!

Well as the cheapest servo is also the busiest in our area the fuel will be fresh and cheap so what more can one want. Also this one is only 10c more for 95 than 91 when most are 18c or more extra. They also have an attendant who will pump it for you. Remembering I am in Australia. so no high octane E10 here thank god.

Edited 19 August, 202519 Aug by Exkiwi

On 18/08/2025 at 11:07, astr0b0y said:

I only use e10 (Melbourne), have done for years. And I have lots of Skoda driving friends who only use 91 and have never even thought about RONs. No issues at all.

Have tried 95 for a 6 months to see if there was any change in efficiency - there was not.

Skoda must have better market penetration in your state than mine. No friend of mine has one although one guy I'm on 'nodding terms' with down the road has a Kodiaq. Do you belong to a Skoda club?

While it is a temptation to generalise about using 91RON from your experiences you might like to consider there are situations where it might be poor advice.

For many years European manufacturers restricted what they sent us due to our poor fuel quality which centred principally around sulphur content. When I first came to Aus near 40 years ago the exhaust literally stank like a New Zealand volcanic spring.

Over time fuel standards improved dramatically so that diesel match Euro standards and petrol was substantially improved.

Currently max sulphur content for Euro and US petrol standards are 10ppm and Australian are 150ppm for standard (91) and 50ppm for premium (95/98).

The VW group identified that vehicles fitted with PPF (petrol particulate filter), now mandated in Europe, could have the unit severely compromised from even one fill of our 91 RON fuel (pure or E10). As far I can remember it was only the Superb 280 4x4 that was imported with the ppf but I really don't know the what the status is now as what cars may, or may not, have a ppf fitted.

Most VW group cars of the last decade would have anti-knock sensors, so possible for lower spec engines like 1.0/1.4/1.8 tsi (with no ppf) could run on 91RON without obvious issues but I suspect it may require a few tanks of higher grad fuel before the ECU advanced timing for better performance/efficiency. As to whether it would be noticeable or not?

I remember that some of VW group higher spec 2.0tsi equipped vehicles (RS, Type R?) imported to Australia have recommended 98RON with 95ROn as a fallback and definitely not 91.

One of Mazda's turbo petrol engines is designed to accommodate 91RON to 98RON (91 RON equivalent is also available in the US), and their blurb said that the 98 RON produced 12kw more in that engine.

At the other extreme my 2003 Toyota Echo's manual quite openly says the engine is designed for Australian 91 RON and while higher RON can be used it is pointless and a waste of money.

Edited 19 August, 202519 Aug by Gerrycan

4 hours ago, Ootohere said:

@PetrolDave No place in the UK as sold 98 ron for over a decade.

But there is E5 97 or 99 ron minimum Super Unleaded on sale.

@Ootohere I know you love being pedantic but really the difference between 97, 98 & 99 in this context is not worth posting about 🤡