95 or 98 RON?

My 3.0Si threw up amber EMLs twice a year or so ago, and both were for Cat 1 and 2 faults.

After resets my BMW Indy added some Cat-A-Clean and told me I should stick to Super-Plus fuel - ideally Shell - as they had better cleaning properties. He said he'd only ever put the good stuff in any petrol-engined BMW!

Since then I've only ever put higher octane fuel in mine and so far so good! (Fingers crossed).

Mind you I've stopped using Shell - they charge at least 10p a litre more for V-Power, whereas it's only an extra 5p a litre for Tesco Momentum. And Tesco is my nearest filling station anyway! :)
 
98 Ron is the stuff to use. Generally better for your engine. Plus a small improvement in fuel economy. Though not enough to cover the difference in cost. But then what cost a happy engine. :wink:
 
Before having the Z4 I had an MGF and this subject was debated on many occasions , I think the concenus of opinion amongst MGF owners at the the time was that apart from the cleaning properties of 98 there was no noticeable improvement in performance , I've run the Z on 98 and can't say I've noticed any difference , as much as I've tried to convince myself to the contrary :)
 
Zulu59 said:
Before having the Z4 I had an MGF and this subject was debated on many occasions , I think the concenus of opinion amongst MGF owners at the the time was that apart from the cleaning properties of 98 there was no noticeable improvement in performance , I've run the Z on 98 and can't say I've noticed any difference , as much as I've tried to convince myself to the contrary :)
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At least there should be less carbon to clean off when changing the head gasket :)
Rob
 
Some people say supermarket stuff it to be avoided! As it's all the shite that no-one else wants, which is why usually its a little cheaper? :?

You better off with something like Shell 95 or Tesco Momentum stuff in this case? Any petrols to be avoided? Any preferences in petrols (e.g. Tesco's momentum has come up a few times). I know sometimes its a matter of location and cost but generally speaking?

Cheers :)
 
Years ago, my Dad had a 2.0 petrol VW Sharan. (I'm one of three kids... we needed the space :poke: )

Repeatedly whenever he filled up at Morrisons, the ECU lights came up. Time and time again. Maybe to do with the ethanol content ?

kis said:
Some people say supermarket stuff it to be avoided! As it's all the shite that no-one else wants, which is why usually its a little cheaper? :?

You better off with something like Shell 95 or Tesco Momentum stuff in this case? Any petrols to be avoided? Any preferences in petrols (e.g. Tesco's momentum has come up a few times). I know sometimes its a matter of location and cost but generally speaking?

Cheers :)
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Scratches Morrison's off the list!
What about Tesco or Sainsbury? They tend to be dotted good distances at work and at the home address. Anyone?
 
kis said:
Scratches Morrison's off the list!
What about Tesco or Sainsbury? They tend to be dotted good distances at work and at the home address. Anyone?
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I'm sure there was a study / tv prog years ago and Tesco momentum came out really well from tests! I'm not sure about the rest of the range though ... momentum also used to have the highest octane rating but shell nitro caught up with that
 
I have always used Momentum99 on my Mini and Z4. I monitored my mileage and fuel usage over two months using standard 95RON and Momentum 98RON (or is it 99? not sure) I noticed that the fuel consumption was 6% better on Momentum99, the car feels more responsive but I can't easily quantify this. The price increase was 4% more, so it seams the right thing to do. Interestingly for two weeks I tried Shell 98 Ron and only got a 2% increase in fuel consumption for a 8% increase in price (admittedly two weeks of test is more subject to variability). I understand both cars use knock detection to advance ignition timing so I would expect similar for Z4. It is much harder to assess on Z4 because fuel consumption is far more affected by driving method (if you know what I mean) than on a N/A Mini.

I am convinced enough to always Momentum99.
 
Generally speaking ALL fuels come from the same UK refineries and ALL meet the same quality standards (EN228 for petrol & EN590 for diesel). The only difference is the additives which may boost octane and help prevent gumming up of fuel lines / injectors etc. There have been rumours in the past that some supermarkets have on occasion imported 'excess production' from outside Europe but I suspect the administrative complexities of doing so are a pretty big deterrent as they would still be legally obliged to meet EN2228 and EN590 if they wanted to sell it in the UK.

That said, Ethanol content does have an impact. Ethanol is added by almost all manufacturers as it's a cheap easy way to boost octane rating and because it's an oxygenator it results in less harmful emissions (the primary reason for government legislation for it's use). The vast majority of fuels in this country are UPTO 5% ethanol but 10% has been rumoured for a long time and is undoubtedly on it's way. It's supposed to be clearly identified on the pump in terms of an E no. e.g. E5, E10 etc.

Ethanol has a lower calorie value than petrol so inevitably mpg suffers (about 3-5% for E10) BUT it has good anti-knock properties so may allow more ignition advance and hence power output. It's very hygroscopic unfortunately meaning it absorbs moisture. This can be a problem if you leave fuel sat in a tank for prolonged periods as you can get quite a lot of water forming at the bottom of the fuel tank and cause starting problems / rough running. Finally it can react quite badly with certain plastics, rubbers and seals, but any car manufactured after 2002 is likely to be fine and EVERY car manufactured after 2011 HAS to be compatible by law.
 
I always use 98 unless I have no choice. The reason being the Z4's are prone to O2 sensor issues and changing fuel grade can trigger them easily.

I had it when I did the NC500 and had no chce bu to use 95 and within 10 mile the light had come on.

Likewise when I was in France and TAZ filled up with 98 instead of his usual 95 his light came on.

Both times I managed to reset both cars though.

So I'm not advocating 98, but suggesting your car will adapt to one and where possible stick to the same grade and brand of fuel.
 
Smartbear said:
Zulu59 said:
Before having the Z4 I had an MGF and this subject was debated on many occasions , I think the concenus of opinion amongst MGF owners at the the time was that apart from the cleaning properties of 98 there was no noticeable improvement in performance , I've run the Z on 98 and can't say I've noticed any difference , as much as I've tried to convince myself to the contrary :)
Click to expand...

At least there should be less carbon to clean off when changing the head gasket :)
Rob
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the dreaded MG head gasket :rofl:
 
Smartbear said:
kis said:
srhutch said:
Both times I managed to reset both cars though.
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How can you do this, incase it is triggered?
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I think most code readers/apps allow you to reset warning lights :thumbsup:
Rob
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Oh right, didn’t realise I’d get a flat out dash error. Should be a simple enough Carly jobbie then :thumbsup:
 
Wow thread going great guns.
On a personal level I noticed massive difference in my old turbo cars (850 t5 back in the day, and more recently an RS6) regarding supermarkets I don't use Tesco..for some reason none of my cars like it, but Sainsbury's seems fine. The highest bang for the buck I have ever noticed was Agip Super when we lived in Spain, my e36 compact was a totally different animal and id wait until we passed an Agip station to fill up.
On the Zeds.. We'll only a few hard driven tank fulls will tell I suppose...WHAT A SHAME!!!
Anyone else fancy burning up some super in the name of science?
D
 
kis said:
Smartbear said:
kis said:
How can you do this, incase it is triggered?
Click to expand...

I think most code readers/apps allow you to reset warning lights :thumbsup:
Rob
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Oh right, didn’t realise I’d get a flat out dash error. Should be a simple enough Carly jobbie then :thumbsup:
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I used torque on Android with an elm327 Bluetooth dongle. Under a tenner for both in total.
 
Z4 COUPSTER said:
Anyone else fancy burning up some super in the name of science?
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TBH I wouldn't mind, but then like someone said driving style plays a big factor. As does the types of road. As well as how frequently you actually fill up. So me running a certain type of fuel, and someone else running another... wouldn't really work. I guess what would work is if a few people wanted to fuel up "for science" and perhaps take data for the same set of fuels. For example both fill up with Momentum99 and standard 95 and see the results.
 
kis said:
Z4 COUPSTER said:
Anyone else fancy burning up some super in the name of science?
Click to expand...

TBH I wouldn't mind, but then like someone said driving style plays a big factor. As does the types of road. As well as how frequently you actually fill up. So me running a certain type of fuel, and someone else running another... wouldn't really work. I guess what would work is if a few people wanted to fuel up "for science" and perhaps take data for the same set of fuels. For example both fill up with Momentum99 and standard 95 and see the results.
Click to expand...
I agree if the right foot is heavy, hell breaks loose.
Nice though.
 
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