The consumption on my 2.2 is no different using 95 or 99 RON. I do get a bit of pinking sometimes using the 95 when the engine is under load, uphill and I'm a bit slow changing down so I run on Tesco's Momentum most of the time.
Which Fuel
- Thread starter Geophys
- Start date
- Joined
- Apr 1, 2016
- Points
- 208
- Location
- Maybole , South Ayrshire
- Model of Z
- Z3 Individual Dakar / Orinoco Individual
If i fill my tank with momentum from totally empty it would cost an extra £2.55 over tesco standard unleaded so for me its a small extra cost that i can live with
Mine seems to run fine on all of the mentioned fuels with no appreciable difference in output or fuel consumption. Valves looked brand new when I swapped the manifold to M54B30 a few weeks back.
I would be less concerned about the fuel, and more concerned about the watery mustard that the PCV is dumping into your inlet manifold. Oil catch can/separator stopped this completely, valves are as clean as new.
Fuel can be so car-dependent, my Saab 9-5 2.3 HOT Aero Manual hated supermarket fuel and absolutely flew on 98RON (if you have never driven one, have a go they are like missiles).
Happy motoring.
I would be less concerned about the fuel, and more concerned about the watery mustard that the PCV is dumping into your inlet manifold. Oil catch can/separator stopped this completely, valves are as clean as new.
Fuel can be so car-dependent, my Saab 9-5 2.3 HOT Aero Manual hated supermarket fuel and absolutely flew on 98RON (if you have never driven one, have a go they are like missiles).
Happy motoring.
My background is large diesels and there is a bit more concern when you are ordering fuel by the barge. Worked ten years for one of the manufactures and went through a lot of fuel testing. Even though it was diesel most of the items overlap to petrol.
Octane is simply a measurement of how well a fuel is resistant to premature detonation. Its not a power rating. High strung race engines require higher octane as they are pushing the limits.
I am using BP premium in my car so I can fill it up pretty much anywhere. When it was on the dyno the other day I was getting pinking in the mid range and had to back the tune down to eliminate it. But considering the car is boosted and just shy of 400hp its not something everyone will have to worry about. If I filled it with high octane race fuel I could tune the car up even higher and get even more power out of the same set up. But on the other hand if I ran my car on cheap low grade fuel in the current set up it would have the knock sensors going off all the time reducing the power
I agree with the above comment about a catch can. My fill cap was always gunked up with yellow watery goo. Now that I have a catch can installed and the stock ventilation system removed the engine is super clean and there is no sign of much in the rocker cover.
Octane is simply a measurement of how well a fuel is resistant to premature detonation. Its not a power rating. High strung race engines require higher octane as they are pushing the limits.
I am using BP premium in my car so I can fill it up pretty much anywhere. When it was on the dyno the other day I was getting pinking in the mid range and had to back the tune down to eliminate it. But considering the car is boosted and just shy of 400hp its not something everyone will have to worry about. If I filled it with high octane race fuel I could tune the car up even higher and get even more power out of the same set up. But on the other hand if I ran my car on cheap low grade fuel in the current set up it would have the knock sensors going off all the time reducing the power
I agree with the above comment about a catch can. My fill cap was always gunked up with yellow watery goo. Now that I have a catch can installed and the stock ventilation system removed the engine is super clean and there is no sign of much in the rocker cover.
400bhp in a Z3 yeeeeeeeha!
Interesting stuff on the fuel question and glad you agree on the oil catch can (reduces the possible sources of a vacuum leak also - one pipe in and one out).
Interesting stuff on the fuel question and glad you agree on the oil catch can (reduces the possible sources of a vacuum leak also - one pipe in and one out).
- Joined
- Feb 18, 2016
- Points
- 231
- Model of Z
- Z3M Imola and Z4 (e89)
Interesting, I run the M on as high oct I can get, it certainly does not like 95RON, if I get caught short and have to put it in it pinks on it especially in warmer weather, put 97+ in and no issues, momentum is my favourite choice. The e89 (2.5) doesn't seem to mind any fuel even Tescos 95Ron which the M refuses to use without coughing. Never had any issues with goo in the rocker on any of them though.
In my youth, I had a part time job in a filling station (attendant service) who had 2, 3, 4 and 5 star leaded fuels. If the tanker couldn't get the ordered load into the filling stations tanks by star, the excess was put in another tank with room. Sometimes 5 star into 2 star (and the other way around) and so on - guess this wouldn't be allowed now (even if it was then!); consequently, I have always been a bit sceptical about what you are actually getting.
That said, my 1147cc Triumph Herald convertible (first car) always had 5 star leaded (happy days) to maximise performance (or so the teenager thought!). These days I always put the most rons I can get in my cars; some of us never grow up thank fully!!
That said, my 1147cc Triumph Herald convertible (first car) always had 5 star leaded (happy days) to maximise performance (or so the teenager thought!). These days I always put the most rons I can get in my cars; some of us never grow up thank fully!!
There is so much talked about fuel quality, particularly on car forums. There are a number of articles I have read and features in magazines and TV debunking most of this, but still the arguments persist.
All petrol in this country has to conform with a minimum standard and that is produced in the refinery processing stages, producing either Premium 95RON or Super 97/98RON which then goes to multiple storage tanks.
The standard gets updated every few years to account for different inclusions or fuel composition. For instance, it is just about to change again to allow for up to 10% ethanol content from the current 5% maximum.
Once it is stored as base fuel, an additional additive package is added, normally specified by each customer (be that Tesco, BP, Shell or whoever) which can add extra detergents, anti-corrosives, cleaning agents and/or lubricant chemicals. The lower priced fuels would normally be expected to have less of these additives, a basic package if you like, as opposed to the likes of V-power or Momentum which will contain more or different chemicals.
All cars sold in this country are able to run on the base fuel, 95RON with basic additive package. (Although E10 fuel may not be suitable for all cars made before 2000). This is likely to be supermarket fuel if you like. It is better quality than in many other countries where cars are sold and manufacturers have to ensure their vehicles will run reasonably well and reliably on the lowest quality petrol they will encounter for obvious reasons. That is one of the reasons that the engine management system is usually set at such a conservative level of tune, plus knock sensors etc are used to prevent damage from poor quality fuel.
That doesn't mean that the minimum standard fuel is always the best option in quality to value terms, as we all know that over time deposits build up from dirt, moisture, evaporation and oxidation, which reduce the performance of fuel system components like pumps, filters and injectors and products of combustion and oil breakdown occur in the cylinders. Therefore fuel companies argue that their particular fuel additives are the best at maintaining the performance of the car for longer or improving the performance of older more clogged engines.
The question for me then is how much more value will I get from using say Shell Premium as against Sainsburys, or super unleaded with additional additives, that is, are V-Power/Momentum etc worth the extra cost. My compromise is to go for a three to one policy. Three fills of supermarket 95RON with one fill of Shell V-Power. My thinking is that I am getting some of the benefits of the additional additives and a slightly higher octane, without all of the cost. If I had a car that was recommended to run on 97RON I would probably use that exclusively, or at least reverse my three to one policy to favour it.
Another issue for me is that of contamination in forecourt storage tanks, road tankers (or less likely refinery tanks), with particulates or water, which can cause even the best quality fuel to cause rough running, knocking or engine management sensor faults. It is therefore often recommended that you fill up at busy centres with fast turnovers of fuel loads and supermarkets have the fastest turnover rates.
It is also true since fuel is sold by volume not weight that you should avoid filling during the higher daytime temperatures, due to evaporation (on a hot day you can see it vaporising around the tank filler neck) and density changes, which are small but not negligible. Basically you get less for your money and possibly less of the lower chain length molecules that help smooth combustion.
I don't claim this is definitive, just my thoughts, backed by what I have read and my own limited knowledge.
All petrol in this country has to conform with a minimum standard and that is produced in the refinery processing stages, producing either Premium 95RON or Super 97/98RON which then goes to multiple storage tanks.
The standard gets updated every few years to account for different inclusions or fuel composition. For instance, it is just about to change again to allow for up to 10% ethanol content from the current 5% maximum.
Once it is stored as base fuel, an additional additive package is added, normally specified by each customer (be that Tesco, BP, Shell or whoever) which can add extra detergents, anti-corrosives, cleaning agents and/or lubricant chemicals. The lower priced fuels would normally be expected to have less of these additives, a basic package if you like, as opposed to the likes of V-power or Momentum which will contain more or different chemicals.
All cars sold in this country are able to run on the base fuel, 95RON with basic additive package. (Although E10 fuel may not be suitable for all cars made before 2000). This is likely to be supermarket fuel if you like. It is better quality than in many other countries where cars are sold and manufacturers have to ensure their vehicles will run reasonably well and reliably on the lowest quality petrol they will encounter for obvious reasons. That is one of the reasons that the engine management system is usually set at such a conservative level of tune, plus knock sensors etc are used to prevent damage from poor quality fuel.
That doesn't mean that the minimum standard fuel is always the best option in quality to value terms, as we all know that over time deposits build up from dirt, moisture, evaporation and oxidation, which reduce the performance of fuel system components like pumps, filters and injectors and products of combustion and oil breakdown occur in the cylinders. Therefore fuel companies argue that their particular fuel additives are the best at maintaining the performance of the car for longer or improving the performance of older more clogged engines.
The question for me then is how much more value will I get from using say Shell Premium as against Sainsburys, or super unleaded with additional additives, that is, are V-Power/Momentum etc worth the extra cost. My compromise is to go for a three to one policy. Three fills of supermarket 95RON with one fill of Shell V-Power. My thinking is that I am getting some of the benefits of the additional additives and a slightly higher octane, without all of the cost. If I had a car that was recommended to run on 97RON I would probably use that exclusively, or at least reverse my three to one policy to favour it.
Another issue for me is that of contamination in forecourt storage tanks, road tankers (or less likely refinery tanks), with particulates or water, which can cause even the best quality fuel to cause rough running, knocking or engine management sensor faults. It is therefore often recommended that you fill up at busy centres with fast turnovers of fuel loads and supermarkets have the fastest turnover rates.
It is also true since fuel is sold by volume not weight that you should avoid filling during the higher daytime temperatures, due to evaporation (on a hot day you can see it vaporising around the tank filler neck) and density changes, which are small but not negligible. Basically you get less for your money and possibly less of the lower chain length molecules that help smooth combustion.
I don't claim this is definitive, just my thoughts, backed by what I have read and my own limited knowledge.
Excellent research and thought process.
I have been led to believe (although I'm not sure I do believe) that super unleaded does not currently contain ethanol at all. My Z3 isn't my worry, but my Westfield with its 1994 fuel lines and last century modified 2.0 litre Ford Pinto engine is a worry. It is suitable for unleaded fuel and by implication as it has never shown any failures, it's happy with E5. Ten percent ethanol is a concern though. It already suffers sticky float chamber valves in the Dellorto carbs if left unused for more than a few weeks over winter, and I worry than dissolved components of rubber hoses etc., may exacerbate this. No point in super unleaded for it as the engine has no computer managing the timing and it would run just the same.