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Will using standard 95 fuel damage my engine on my 2018 Leon cupra?

Nov 16, 2022
9
1
South Wales
I’ve been using standard 95 fuel not knowing my fuel cap said use 98/ supreme fuel, stupid I know but I’ve been using normal fuel since I had it in march 2022 an driven it pretty hard over the summer. It runs fine and haven’t had any problems but I’ve just realised I should be using supreme fuel so would it have caused any damage by using standard fuel??
 

CalJames

Modification Addict
Jun 25, 2019
342
157
North Wales
In that time not really, however the E10 petrol is pretty awful so don't be surprised if you feel it run a lot better on premium E5 fuels.
I know a guy that runs his M3 on Tesco standard unleaded 90% of the time and he doesn't drive it lightly, so I wouldn't worry too much.
 

jonny_w

Active Member
Jun 26, 2014
120
29
If you read the handbook it states that if you run on 95 unleaded expect a power loss. In my ownership I have only run on 97/99 and was told by the mechanic in seat that it will be more economical.
 
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Nov 16, 2022
9
1
South Wales
In that time not really, however the E10 petrol is pretty awful so don't be surprised if you feel it run a lot better on premium E5 fuels.
I know a guy that runs his M3 on Tesco standard unleaded 90% of the time and he doesn't drive it lightly, so I wouldn't worry too much.
That’s good to hear, cheers for the reply. I should of checked when I first bought the car I just assumed the supreme fuel wouldnt make a difference🤦‍♂️I’ve filled up using 97 unleaded earlier but going to try esso 99 next time
 
Nov 16, 2022
9
1
South Wales
If you read the handbook it states that if you run on 95 unleaded expect a power loss. In my ownership I have only run on 97/99 and was told by the mechanic in seat that it will be more economical.
Wish I read it when I first had the car, was too busy enjoying it I think😂 the most it was showing on the dyno a few months ago was 285hp, meant to be 300 so must of been the crap petrol I was using
 

H Rafiq

Active Member
Jan 5, 2022
1,101
444
I use either Shell V-Power or Tesco Momentum in my Leon Cupra 280. Both 99 octane. I think the 300 is supposed to be 295bhp. The fuel could be why it’s putting out 10bhp less on the dyno.
 
Nov 16, 2022
9
1
South Wales
I use either Shell V-Power or Tesco Momentum in my Leon Cupra 280. Both 99 octane. I think the 300 is supposed to be 295bhp. The fuel could be why it’s putting out 10bhp less on the dyno.
Definitely going to start using that from now on. just hoping I haven’t caused any damage. had it on 27k miles so not sure what fuel was used before me, and now I’ve done almost 10k miles with 95 unleaded🤦‍♂️
 

mty12345

Active Member
Jun 17, 2011
3,907
538
bristol
Definitely going to start using that from now on. just hoping I haven’t caused any damage. had it on 27k miles so not sure what fuel was used before me, and now I’ve done almost 10k miles with 95 unleaded🤦‍♂️
You won't have done any lasting damage, it's a bit of an all or nothing thing when it comes to knock! If it's allowed to go unchecked then it'll quicky blow an engine to bits, but 99% of modern engines (including yours) have knock sensors, so the ECU will use that info to retard the timing (and/or reduce boost) before anything snaps. You would probably have been losing quite a bit of torque under hard acceleration though.

All performance cars should be run on a minimum of 98 from the factory, but most can also take advantage of 99. Tesco's 99 is usually a fair bit cheaper than shell and esso where i live.
 
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Nov 16, 2022
9
1
South Wales
You won't have done any lasting damage, it's a bit of an all or nothing thing when it comes to knock! If it's allowed to go unchecked then it'll quicky blow an engine to bits, but 99% of modern engines (including yours) have knock sensors, so the ECU will use that info to retard the timing (and/or reduce boost) before anything snaps. You would probably have been losing quite a bit of torque under hard acceleration though.

All performance cars should be run on a minimum of 98 from the factory, but most can also take advantage of 99. Tesco's 99 is usually a fair bit cheaper than shell and esso where i live.
Ah that’s reassuring thanks! wish I knew all this sooner😂 it does so well now so can’t wait to see how it performs with better fuel.

I’m going to use esso as I’ve read they don’t use any ethanol at all in their 99, think my engine deserves it after all that crap e10 lol
 

mty12345

Active Member
Jun 17, 2011
3,907
538
bristol
Ah that’s reassuring thanks! wish I knew all this sooner😂 it does so well now so can’t wait to see how it performs with better fuel.

I’m going to use esso as I’ve read they don’t use any ethanol at all in their 99, think my engine deserves it after all that crap e10 lol
No worries, and IMO they should make the 98 requirement much more obvious on the fuel cap, rather than just putting it on the sticker. There are lots of people out there using the wrong fuel without realising it.

You're right about Esso. They have E5 on the pump as that is a legal requirement, but the actual fuel contains no ethanol. Ethanol in itself isn't damaging to modern fuel systems, but petrol has a much higher (30%) energy density. A litre of petrol without ethanol should give you more MPG than a E5 or an E10.
 

mty12345

Active Member
Jun 17, 2011
3,907
538
bristol
Esso better than Tesco and Shell?
They are all the same in terms of octane and performance, but esso should give you more miles to gallon. That is probably offset by the fact that tesco is cheaper though. Additives also come into it, but who knows which one is best in terms of that
 
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Nov 16, 2022
9
1
South Wales
No worries, and IMO they should make the 98 requirement much more obvious on the fuel cap, rather than just putting it on the sticker. There are lots of people out there using the wrong fuel without realising it.

You're right about Esso. They have E5 on the pump as that is a legal requirement, but the actual fuel contains no ethanol. Ethanol in itself isn't damaging to modern fuel systems, but petrol has a much higher (30%) energy density. A litre of petrol without ethanol should give you more MPG than a E5 or an E10.
Yeah honestly I didn’t even know there was a sticker on the petrol cap. Lucky I seen a post on Facebook which made me curious on what fuel I needed. I’ve only recently got into cars since I had my cupra so didn’t have a clue about fuel, and others are probably in the same situation.
I’m gonna experiment with esso and Tesco to see what feels best. I filled up with esso 97 yesterday and definitely feels smoother already so I’m excited to try 99. Thanks for the advice mate been very helpful👍
 
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Jazzjames

Active Member
Sep 13, 2018
160
68
Germany
Also, fretting over 10bhp on a dyno run is nothing to worry about. Who is to say that dyno is not 3% pessimistic? 300ps =295bhp by the way.
 
Nov 16, 2022
9
1
South Wales
Also, fretting over 10bhp on a dyno run is nothing to worry about. Who is to say that dyno is not 3% pessimistic? 300ps =295bhp by the way.
True but did have a few runs on the dyno and the most it was putting out was 285, was less on the first run though. So maybe it was the fuel maybe not
 

Jazzjames

Active Member
Sep 13, 2018
160
68
Germany
The only thing a dyno can tell you with accuracy is relative performance. 285bhp on 95 unleaded sounds spot on without knowing how other cupras have performed on that same dyno.

As far as damage goes, you are allowed to run the car on 95, but with a slight loss of power, so no issue there. If you’ve been ragging the car before the oil is up to temperature, that’s another story…
 

jonny_w

Active Member
Jun 26, 2014
120
29
I find with my DSG cupra it will not let me over rev over a certain point until the oil is up to temp, to be fair though I had to try pulling out but normally the car sits to warm or my rule is 15min of driving before hard.
 
Nov 16, 2022
9
1
South Wales
The only thing a dyno can tell you with accuracy is relative performance. 285bhp on 95 unleaded sounds spot on without knowing how other cupras have performed on that same dyno.

As far as damage goes, you are allowed to run the car on 95, but with a slight loss of power, so no issue there. If you’ve been ragging the car before the oil is up to temperature, that’s another story…
Fair point!

that’s good to hear about the fuel. I have put my foot down when the oil is only about 60/70 degrees but only a few times. I always let it get to above 90 before I drive it hard. Is that bad?

I find with my DSG cupra it will not let me over rev over a certain point until the oil is up to temp, to be fair though I had to try pulling out but normally the car sits to warm or my rule is 15min of driving before hard.
I haven’t noticed that with mine with the revs tbh. But I won’t drive it in high revs until the oil is at least past 90. When I race it’s always up to max temp before hand. Yeah 15 mins is definitely a good rule
 

Jazzjames

Active Member
Sep 13, 2018
160
68
Germany
Fair point!

that’s good to hear about the fuel. I have put my foot down when the oil is only about 60/70 degrees but only a few times. I always let it get to above 90 before I drive it hard. Is that bad?


I haven’t noticed that with mine with the revs tbh. But I won’t drive it in high revs until the oil is at least past 90. When I race it’s always up to max temp before hand. Yeah 15 mins is definitely a good rule
I'm sure it will be ok if you don't do it all the time. I'd let the oil warm up to 90C before going bananas, though.
 
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