Does buying the more expensive fuel actually make a difference?

[Zirax]

Originally Posted by Feek

Is yours the petrol or the diesel version Focus? I'm guessing petrol.

Should have said, its a petrol 1.8

[Grandad]

It very much depends on your car, if your car is mapped for 95 RON then put that in , very few are mapped for 97/98 and these are generally performance cars ( I don't mean hot hatch type stuff here )

Turbocharged petrol cars generally show the biggest gains from premium fuels

I am referring to petrol cars in the above as I don't know much about diesels as I don't want to talk to strange people in brown cords and dodgy beards

[Garp]

Top Gear also did an investigation into this with different types of cars. Those with full on engine mapping saw the best benefits, those with nowt got little if anything. Mine won't show any improvement because its EMU isn't very fancy at all and it doesn't have many sensors. Apparently the key thing is to have a "knock" sensor? I've been told that enables the EMU to change the timing of the engine to be as efficient as possible and enables it to take advantage of the higher RON. Stuff like VTEC engines will see some advantage. Whether its cost effective is a whole other argument I know someone who swears by it and sees a nice efficiency gain that more than offsets the cost.

I have a toggle jumper thing under the bonnet. Unplug it, plug it the other way around and it changes the engine map to use a different RON fuel. Unfortunately its for the old (93 I think?) and current 95 only, no 97 option

[Fayshun]

Originally Posted by Garp

Apparently the key thing is to have a "knock" sensor?

?

[Muban]

As already said it very much depends on your car. Mine has the ECU mapped for higher RON fuel and the knock sensor. I get a clear performance difference and always use V-Power or Ultimate (well where possible, sometimes some petrol stations don;t have it and i have to use the other muck ). Poor Tochi doesn't like it when I give him the cheap stuff

[mejinks]

Are we going to have a Supermarket isn't as good as Shell debate? I hope not.

Basically, you WILL see a difference if you are using supermarket fuel and then change to V-power PROVIDING you have a car with adaptable ECU. This is because supermarket fuel is basically the same as say Shells normal unleaded, it just doesn't have the additives such as detergents and stuff that Shell normally put in.

The last time I changed to Optimax it took 4 tanks of the stuff before the car learned the new fuel and I can say it did make a big difference to me. Also, on a Dyno run, my car made 197 HP whereas it should only have made 193 as standard.

[Garp]

With my car which has no fancy ECUs or knock sensors and the like, is it worth chucking a tank of the expensive stuff in it every now and then for the other additives? Give the engine a bit of an internal cleaning?

[mejinks]

Originally Posted by Garp

With my car which has no fancy ECUs or knock sensors and the like, is it worth chucking a tank of the expensive stuff in it every now and then for the other additives? Give the engine a bit of an internal cleaning?

The only benefit is to the oil company. You are better off chucking some redex injector or carb cleaner in every 10k miles or so.

[Will]

Originally Posted by Garp

With my car which has no fancy ECUs or knock sensors and the like, is it worth chucking a tank of the expensive stuff in it every now and then for the other additives? Give the engine a bit of an internal cleaning?

It takes several tanks worth to start doing any "cleaning" - frankly in a N/A car that hasn't been mapped to 97+ RON there's very little point.

Owing to the nature of FI'ed cars the calorific values of fuel do become very important. With a proper map alone you can gain a significant increase in power. Obviously this is all down to how well the ECU adapts and also if it has a mapping to cope with it.

Mejinks, I'd disagree, supermarkert SUL is certainly not as good as Optimax (numerous magazines and reports have proved this, as have dyno runs for my car and bike), Tesco 99RON is a bit of a con, they've increased solely the RON rating but leave the MON untouched - which is equally as important. MON simulates more severe operation that might be incurred at high speed or high load whereas RON is low load and speed. This all makes it more efficient at burning fuel (once again if your car can adapt/cope with it).

By having a knock sensor the system allows an engine to operate very near its detonation limit -thereby improving power and efficiency. If the ECU can incorporate the readings from this sensor it can draw all the benefits from the better fuel.

[Grandad]

Originally Posted by Le Hoff

Mejinks, I'd disagree, supermarkert SUL is certainly not as good as Optimax .

]

I think he was referring to 95/97 Ron petrol

The supermarkets buy it on the Rotterdam spot market, so you could quite easily be getting Shell fuel from asda ( 95 )