Does Supermarket Fuel Produce Lower MPG?
Discussion
kambites said:
R300will said:
kambites said:
I've run cars on five year-old petrol without any obvious decrease in performance.
Where did you find 5 year old petrol? 
Brigand said:
Over the past year, I've traveled home to my parents in a GTV, Mk1 MX-5 and an Almera GTi. It's a trip of about 150 miles.
When going there, I'll fill up with either BP 95RON, or similar Tescos fuel. The journey is 95% motorways, and driving most of the journey at 70-80mph, I'll use around half a tank of fuel.
Coming back though, I fill up at the local TOTAL garage, and doing the same speeds, I've gotten home having used just less than quarter of a tank, the same thing has happened in the three different cars I've used in the past.
Clearly the TOTAL fuel is much better quality than what the other garages provide, and I used to consider them one of the lower-end fuels.
So it is uphill and into the prevailing wind on the way to your parent's then downhill with the wind behind on the way back? When going there, I'll fill up with either BP 95RON, or similar Tescos fuel. The journey is 95% motorways, and driving most of the journey at 70-80mph, I'll use around half a tank of fuel.
Coming back though, I fill up at the local TOTAL garage, and doing the same speeds, I've gotten home having used just less than quarter of a tank, the same thing has happened in the three different cars I've used in the past.
Clearly the TOTAL fuel is much better quality than what the other garages provide, and I used to consider them one of the lower-end fuels.
Next time you drive past a refinery just take a look, the tesco tanker is queing behind the bp tanker, behind the texaco behind the jet tanker behind the morrisons etc. Fuels come from the same refineries and must reach a set standard, the fuel is the same no matter where you bought it.
R300will said:
I think its a bit quicker than that. When we used to go on holiday for 2 weeks and dad had filled the car to go ot the airport he said he noticed a difference in performance between going down and coming back. The smaller and therefore more volatile alkanes will have evaporated off in two weeks. Depending on ambient temp of course.
Until fairly recently (when decent knock sensors became fairly widespread) if fuel lost potency (effectively lost RON) you wouldn't get "less power", you'd get knocking/misfiring/limp mode in most cars.A mate of mine recently 'acquired' a few barrels of Unleaded which had been stored for 'a least 5 years'. He threw some into his car and he swears he cannot tell the difference (and it's an older car where I'd have expected to see some knocking if the fuel had lost it's "boom").
The odds are that your Dad thought the car felt slower because you'd all eaten and drunk for England and brought back a metric tonne of duty frees and wicker donkeys
Piepiepie said:
Likewise, my ST220 runs like s
t on BP Ultist, but runs fine on BP peasant fuel.
Assuming Ultimate is higher RON (I don't keep up with this stuff) I'd say your engine lacks a proper knock sensor - or it's not working as intended perhaps.t on BP Ultist, but runs fine on BP peasant fuel.It's amazing how long it's taken some cars to get proper ECU/knock sensor tech. - I was astonished back when I had a Civic VTi (1.8) that it had no knock-sensor whatsoever (and it knocked like a partially derailled train on all fuels).
Mind you, I've been told that it can take a while for some engines to sort out varying RON fuel - it's not an instant switch thing, it "learns" over time by adjusting the timing/fuelling/air mix (in a way which causes minimal carbon build-up or other damage). My Honda simply didn't learn anything (I did - don't buy a Honda!!)
thinfourth2 said:
Classic Grad 98 said:
Tomato ketchup is a bad example. We all know it has to be Heinz. Supermarket ketchup is too sugary/vinegary.
Also F1 sponsorship for tomato ketchup? When!?
Re: fuel- Shell is my nearest and no more pricey than others in the area. The Mondeo gets fuelsave diesel and the Caterham gets V Power. However I have filled the Mondeo at BP in the past and I'm convinced it's smoother and less rattly on BP's boggo fuel than Shell's.
I tryed my caterham on V-Power as everyone raved about itAlso F1 sponsorship for tomato ketchup? When!?
Re: fuel- Shell is my nearest and no more pricey than others in the area. The Mondeo gets fuelsave diesel and the Caterham gets V Power. However I have filled the Mondeo at BP in the past and I'm convinced it's smoother and less rattly on BP's boggo fuel than Shell's.
It went slower
As the octane goes up the calorific value goes down
So unless you have an engine that can adapt to different octane numbers you are pissing money up the wall
I am well aware of the limitations of the was modern engines exploit higher octane fuel.
I'm sad enough to keep details logs of my fuel consumption, and whilst I've never called them statistically viable they've helped me make informed decisions about the fuel I'm putting into my cars.
the 200SX - 2.0 turbo. Noticeably smoother on V-Power, and got about 3% better economy (note this is across 4,000 miles of testing, brim to brim, vs Shell 95 - not jsut a tank here and there). Not enough to offset the price differential but enough to make me feel good about it.
BMW 328i - Ran like crap on morrisons fuel. Ok, that's an exaggeration, but noticeably smoother and more linear on Shell 95 but no bebefit going to V-Power. So Shell 95 it got.
I didn't really believe the hype about "branded" fuels until a mate who is an engieer with Ford and Bench tests their engines told me that they get something like 2% better efficiency out of their engines on premium brands vs supermarket fuel - either 2% more power or 2% better economy, depending on how they choose to tune for that efficiency. IN the real world he says this is negligible vs all the other factors on a cars performance and economy, but nonetheless all fuels are NOT created equal and engines performance DO differ depending on what you feed them.
I'm about to pick up a Subaru, and it'll only be getting V-Power. Turbos need all the help they can get!
the 200SX - 2.0 turbo. Noticeably smoother on V-Power, and got about 3% better economy (note this is across 4,000 miles of testing, brim to brim, vs Shell 95 - not jsut a tank here and there). Not enough to offset the price differential but enough to make me feel good about it.
BMW 328i - Ran like crap on morrisons fuel. Ok, that's an exaggeration, but noticeably smoother and more linear on Shell 95 but no bebefit going to V-Power. So Shell 95 it got.
I didn't really believe the hype about "branded" fuels until a mate who is an engieer with Ford and Bench tests their engines told me that they get something like 2% better efficiency out of their engines on premium brands vs supermarket fuel - either 2% more power or 2% better economy, depending on how they choose to tune for that efficiency. IN the real world he says this is negligible vs all the other factors on a cars performance and economy, but nonetheless all fuels are NOT created equal and engines performance DO differ depending on what you feed them.
I'm about to pick up a Subaru, and it'll only be getting V-Power. Turbos need all the help they can get!
VanBas said:
Interesting stuff here.
So how do you know if your car has a knock sensor to adapt to different grades of fuel? Does my 52 330ci?
Personally always use tesco momentum, never have any trouble and is pretty well priced.
It's not so much whether you car has a knock sensor as to what your car does with the information it sends.So how do you know if your car has a knock sensor to adapt to different grades of fuel? Does my 52 330ci?
Personally always use tesco momentum, never have any trouble and is pretty well priced.
A knock sensor simply detects knocking/pinking - the most basic system would just throw a Diagnostic Event, a smarter system would retard the ignition and a really clever system can adjust fuelling/air mix and allsorts until it stops (in theory, an engine is running perfectly at the brink of knocking I guess?)
My Honda could be run on 95 or 98 RON without mods so it must have had a knock sensor but knocking under load persisted with either fuel which suggests not much was going on as a result of the sensor (or all the sensors were dead!). The Honda Dealer as much as admitted that it was clear the engine couldn't deal with either fuel properly - which isn't a great sign (I should have tried diesel?)
It's worth pointing out that it's always fine to run a petrol engine on a higher octane fuel than it's designed to use, although you wont get any benefit from it unless the engine adapts its timing to take advantage of the extra resistance to combustion under compression; it's only running on a lower one that can cause problems.
Although I suppose theoretically putting more octane (or detergents or whatever) into the fuel reduces the amount of fuel in the fuel, so you get less energy per unit volume in higher octane fuels. The different is pretty negligible though.
Although I suppose theoretically putting more octane (or detergents or whatever) into the fuel reduces the amount of fuel in the fuel, so you get less energy per unit volume in higher octane fuels. The different is pretty negligible though.
Edited by kambites on Monday 30th January 08:41
kambites said:
It's worth pointing out that it's always fine to run a petrol engine on a higher octane fuel than it's designed to use, although you wont get any benefit from it unless the engine adapts its timing to take advantage of the extra resistance to combustion under compression; it's only running on a lower one that can cause problems.
Although I suppose theoretically putting more octane (or detergents or whatever) into the fuel reduces the amount of fuel in the fuel, so you get less energy per unit volume in higher octane fuels. The different is pretty negligible though.
Might explain why I consistantly get the worst mpg out of VPower? (Ford Puma)Although I suppose theoretically putting more octane (or detergents or whatever) into the fuel reduces the amount of fuel in the fuel, so you get less energy per unit volume in higher octane fuels. The different is pretty negligible though.
Edited by kambites on Monday 30th January 08:41
balders118 said:
Might explain why I consistantly get the worst mpg out of VPower? (Ford Puma)
I don't actually know what RON means as such, but I know from using octane additives that the difference the octane makes will be a small fraction of a percent. I very much doubt you could see it in your MPG output. Don't know about the detergents and such like that they add, but I'd be surprised if it's much more. balders118 said:
Fair enough. A mystery then, perhaps.
I've never heard of such a thing, but the only thing I can think of is if you have a weak spark? 95RON is obviously easier to ignite under pressure than 98. Does it feel like it's misfiring on 98? Of course a more likely answer is that the car is adapting correctly to run on 98RON so you're getting more power and you're actually using it.
kambites said:
I've never heard of such a thing, but the only thing I can think of is if you have a weak spark? 95RON is obviously easier to ignite under pressure than 98. Does it feel like it's misfiring on 98?
Of course a more likely answer is that the car is adapting correctly to run on 98RON so you're getting more power and you're actually using it.
No, it doesn't misfire on 98RON.Of course a more likely answer is that the car is adapting correctly to run on 98RON so you're getting more power and you're actually using it.
I didn't any difference in how the engine ran, or the power I was getting from it. Obviously it could be that my driving style changed, but generally it is very consistant. It's down about 5mpg on an average of 5/6 tanks of Vpower I think, and countless tanks of Regular supermarket stuff for the average I get on morrisons.
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