Changing from Unleaded to Superunleaded

[chrisgunton]

Ive been using Unleaded (since times are hard!) but I want to switch up to Super Unleaded as it's best for the car, and everyone reports better MPG with it.

 

Firstly, is it worth it to reduce running costs (better MPG)?

 

Secondly, how quickly should I notice a difference in performance or MPG? 2-3 tank fulls?

[Zugara]

TBH, I have been on both fuels, never never never noticed any difference in MPG or performance. I am sure its all a myth.

 

Thats my 2pence worth.

[rtbiscuit]

cost works out about the same, super gets more mpg but costs more, normal gets less mpg but costs less. the difference between the 2 is small when it comes to mpg when you comapre with cost as well.

 

but more importantly it tells you the car needs super as thats what the cars tuned for.

 

if you want to run on regular, get the engine mapped for it.

[rtbiscuit]

forgot to add, you'll need about 3 tanks through before you see a difference.

[DoubleDeuce1973]

To be honest, you are not going to see a massive increase in MPG, at best you may see enough to balance out the additional cost.

 

The car was designed to run on super so it is worth doing it anyway, just don't look at it as a cost saving.

 

I have signed up to a site that I found on Money Saving Expert which provides details of which companies are selling it the cheapest within a set radius of a post code that you set which has been useful. I have seen a difference of up to 7p per litre from petrol stations within a 5 mile radius of my home. I now tend to fill up at Sainsburys which is currently at 132.9 in my area (cheaper than what some stations are selling unleaded for).

 

May only save you a few quid each fill up but as I drive past the station once per week anyway, I make a point of using it.

[kevlo]

not sure about mpg but it apparently has a big difference to bhp. Fifth gear did an independant test on 3 cars, supermini, saloon and a performance car (subaru impreza).

 

it didnt make much difference at all on the non performance cars but on the scooby it made a huge difference about 40-50 bhp if i remember correctly. it may be different with the 350z being a bigger engined non turbo car though

[waltzinblack]

not sure about mpg but it apparently has a big difference to bhp. Fifth gear did an independant test on 3 cars, supermini, saloon and a performance car (subaru impreza).

 

it didnt make much difference at all on the non performance cars but on the scooby it made a huge difference about 40-50 bhp if i remember correctly. it may be different with the 350z being a bigger engined non turbo car though

 

You sure they weren't using that special BP 100+ Octane race fuel that they sell at like, 8 select petrol stations near race courses?

 

Not trying to start an argument, but I seriously doubt that Super gives you that much more over normal. Maybe 10-15 but not 40. I thought the main benefits of super were slightly cleaner and better additives for the engine, and a little more power.

[DoubleDeuce1973]

not sure about mpg but it apparently has a big difference to bhp. Fifth gear did an independant test on 3 cars, supermini, saloon and a performance car (subaru impreza).

 

it didnt make much difference at all on the non performance cars but on the scooby it made a huge difference about 40-50 bhp if i remember correctly. it may be different with the 350z being a bigger engined non turbo car though

 

You sure they weren't using that special BP 100+ Octane race fuel that they sell at like, 8 select petrol stations near race courses?

 

Not trying to start an argument, but I seriously doubt that Super gives you that much more over normal. Maybe 10-15 but not 40. I thought the main benefits of super were slightly cleaner and better additives for the engine, and a little more power.

 

No way that super gives 40-50 bhp improvement, I would be shocked if it even gave 10.

[kevlo]

i know i doubted it myself, i may have exagerated as ive just found this on another forum

 

 

Just seen a 5th Gear fuel comparison test whilst watching a repeat on Dave.

 

They tested a bog standard Clio, a Golf GTI Mk5 and an Impreza STi (MY06).

 

They reckoned that there was no effect on the clio as its not a performance car, the Golf gained an extra 12bhp using Optimax compared to std supermarket fuel and Impreza results were as follows:

 

Std Supermarket Fuel: 235bhp

 

Ultimate 97: 246bhp

 

V Power 98: 258bhp

 

 

I was way out with 40 but i think 23bhp is a decent difference. one that you should definately notice

[DoubleDeuce1973]

That still seems pretty high to me. Like I say, I would be shocked but quite happy to be proved wrong.

[rtbiscuit]

not sure about mpg but it apparently has a big difference to bhp. Fifth gear did an independant test on 3 cars, supermini, saloon and a performance car (subaru impreza).

 

it didnt make much difference at all on the non performance cars but on the scooby it made a huge difference about 40-50 bhp if i remember correctly. it may be different with the 350z being a bigger engined non turbo car though

 

You sure they weren't using that special BP 100+ Octane race fuel that they sell at like, 8 select petrol stations near race courses?

 

Not trying to start an argument, but I seriously doubt that Super gives you that much more over normal. Maybe 10-15 but not 40. I thought the main benefits of super were slightly cleaner and better additives for the engine, and a little more power.

 

No way that super gives 40-50 bhp improvement, I would be shocked if it even gave 10.

 

its not a gain of 40-50 bhp on super, it means you get the full performance of the car, becuase thats what its tuned to. by running on unleaded, your loosing 40-50bhp.

[kevlo]

That still seems pretty high to me. Like I say, I would be shocked but quite happy to be proved wrong.

 

i think rt biscuit is right. you wouldnt be adding 23 bhp to the 300 the car already has. by having 95 ron supermarket petrol you would be running at 277 bhp. as said the impreza and the zed are very different cars so it may differ.

 

as for proving it. thats exactly what fifth gear did. it was done on a rolling road with official torque and power graphs/figures etc

[waltzinblack]

I'm reading lots of things now on the internet about this..

 

Something about Super Unleaded being better for cars running turbos with high boost pressures (perhaps why that test saw such a change in the Impreza? Do Imprezas use high boost pressures? I wouldn't know.. just a thought)

 

Also some things about Shell V-Power additives actually being BAD for your engine by cleaning it too well... or something. I would be nice for the petrol god to properly clear these rumours up!

 

I always use Super though, because that's what the owners manual recommends. Might leave off the V-Power though. Tesco the best bet?

[DoubleDeuce1973]

i think rt biscuit is right. you wouldnt be adding 23 bhp to the 300 the car already has. by having 95 ron supermarket petrol you would be running at 277 bhp. as said the impreza and the zed are very different cars so it may differ.

 

as for proving it. thats exactly what fifth gear did. it was done on a rolling road with official torque and power graphs/figures etc

 

Yeah, fair point, rtbiscuit is probably right, I didn't think about it that way

[kevlo]

ive always used tesco which is now called momentum i think. its got the highest ron rating at 99. im presuming thats a good thing

[rtbiscuit]

there was a thread or a link to a thread on here where they tested different fuels out on a dyno. tesco came out the best

 

by that i mean it gave the best BHP figure

[Voodoo Vix]

I get about 3mpg more on super so not a big difference but I use it because its what it says to, if I can't get it though, I have no problem with putting the normal stuff in just prefer not to.

[Dblock]

there was a thread or a link to a thread on here where they tested different fuels out on a dyno. tesco came out the best

 

by that i mean it gave the best BHP figure

 

That was also funded by tesco so its crazy biased, also im sure they compared it to optimax not v power.

[rtbiscuit]

there was a thread or a link to a thread on here where they tested different fuels out on a dyno. tesco came out the best

 

by that i mean it gave the best BHP figure

 

That was also funded by tesco so its crazy biased, also im sure they compared it to optimax not v power.

 

i thought it was an independent test done by a tuner. would need to find it to see.

[Dblock]

there was a thread or a link to a thread on here where they tested different fuels out on a dyno. tesco came out the best

 

by that i mean it gave the best BHP figure

 

That was also funded by tesco so its crazy biased, also im sure they compared it to optimax not v power.

 

i thought it was an independent test done by a tuner. would need to find it to see.

 

The tuner was funded by tesco il look for it later.

[Peter10]

Funny, I was wondering the same thing today. I will be looking at getting down to Abbey soon and didn't want to be laughed at when I say I used regular unleaded .

 

 

[rtbiscuit]

they are developing a map for unleaded tuning

[GT4 Zed]

Why would one use unleaded in the first place beats me as its false economy! As covered already the car is mapped from factory with super and when you look at the cost of running both the apparent cost benefits using unleaded do not outweigh the risk of premature failure.

At the very least the cost difference is 5-7p/l and on a full tank(assuming bone dry its £5.6 @ 7p/l difference! @ 6K miles/yr assumming 300miles per full tank that works 20 full tanks/ yr = circa £100 more . but a knackered engine is worth £1500-2K excluding fitting

The argument of gains in bhp etc really is a none starter......its all about running the car optimally. you can aswell put mineral oil to save money or not even drive it at all

 

On another note my experince is the care never falters on super and the rare occassion i toped up with 95 oct it pinked to hell. yes one mighty say because its tuned but we all know high oct means running cooler, less risk of det so the ecu can run more advance and as a result more pwr.

[Chris`I]

For those that run 95RON all the time, RTFM - I'm sure it states only to run 95RON in emergencies and even then get Super back in it ASAP.

 

Just because you cant feel it loosing power doesnt mean bad things arent going on. I will leave you to google what happens when you run a car on high det map all the time, its not good. You may be lucky and the car may run "ok" but you may also be left with a nice bill as Bennett says. The car is tuned to run 98+, so why try and be cheap and put less in? It thinks it has 98RON in it, and when it doesnt its constantly winding back the timing, but it only knows to do that because it gets det and winds back the timing

[tmJak]

You don't buy a performance car to save money. Nissan recommends using super unleaded, so use super unleaded