Fuel - 91 vs 95 RON & above

lokets · 03-03-2006, 02:01 AM

Hi. I knew there were discussions about fuel before but like to know in summary:

1. Fiesta can handle 91 RON fuel, yes?

2. Though cheaper, does 91 RON fuel adversely affect the engine performance?

3. And, if 95 RON or above fuel is used, does this translate to fuel efficiency, and if so, how much improvement (in terms of distance per tank, or km/L) did you experience?

Thank you for your valuable feedback. :evil_laug

xurbanx · 03-03-2006, 03:49 AM

1. I use the normal unleaded on my LX, I think it's 91 RON
2. Don't know about the Zetec's but mine's filled with unleaded, the engine I guess make's more noise? A bit less smooth than using the 95.
3. I thought I'd experimented with 95 for a week on my LX, I've found that it run's a tad smoother, less engine noise, but I felt that it used up a lot quicker.

Like I said, it's not exact figures, but what i've experimented with (: Factor in that I did 120km's per day during that week.

Scareybear · 03-03-2006, 09:53 AM

I normally use Optimax, I find it lasts longer, goes harder, and smoother.

mitch_lx · 03-03-2006, 10:47 AM

I used to use optimax, i prefer BP ultimate now. Every few months i change but i always find myself going back to ultimate (ive only ever used 98 in the car since new)

So i cant offer any insight into different RON fuels. :P

But with my mum's 99 model Honda Civic, the engine is very noisey and guttless (automatic) especially on 91 octane, for a few tanks i made her put 98 in. Even she said she noticed a difference, it was less noisy, got slightly more km per litre and felt a little more eager.

RichieMK6 · 03-03-2006, 10:50 AM

u should always stick to the same fuel and never change , when u change is when u will notice little changes

Pieoter · 03-03-2006, 02:05 PM

When i first got my car it was filled with 91ROn fuel and didn't like it one bit. Not sure it was simply an issue with the ecu not being able to adjust quickly enough (It only had 17km on it) but it did get MAJOR pinging off lights. So i feathered it to the petrol station and filled the tank with 98ROn and havn't gone back.

Danny · 03-03-2006, 02:10 PM

Hey guys,

Theres actually a reason behind reduced performance on 91 RON Fuel. Truth is that the Fiesta is not meant to be run on anything lower than 95RON. They were tuned for this fuel. Anything higher than 95 will not increase performance due to popular beleif.

As they have been tuned for 95, If anything lower is added to the tak, then the Fiesta's ECU de tunes the engine for running on the lower octane fuel. This is where you guys experience the drop in driving quality. As soon as youre back on 95, it will run at full kick again. All 74kW of it hehehehehe.

xurbanx · 03-03-2006, 08:11 PM

^ Does that include Auto LX's Danny? (: If so, the fiesta's getting a dose of 95 tonight (:

Danny · 03-03-2006, 08:15 PM

Yep H. All of em.

joshf2 · 03-03-2006, 10:16 PM

Quote:

Originally Posted by Danny

Hey guys,

Theres actually a reason behind reduced performance on 91 RON Fuel. Truth is that the Fiesta is not meant to be run on anything lower than 95RON. They were tuned for this fuel. Anything higher than 95 will not increase performance due to popular beleif.

As they have been tuned for 95, If anything lower is added to the tak, then the Fiesta's ECU de tunes the engine for running on the lower octane fuel. This is where you guys experience the drop in driving quality. As soon as youre back on 95, it will run at full kick again. All 74kW of it hehehehehe.

this is the knock sensor working. because the motor runs a reasonably high compression ratio (11.0:1), the risk of detonation is much higher with a low octane fuel. the ecu then retards the ignition (ie sparking later in the stroke) which in turn produces less power.

with regards to 95 vs 98, i think that the difference some people notice relates to the difference in specific energy of the different fuels. 98 is meant to have more specific energy than 95.

FlaminFiesta · 04-03-2006, 11:09 AM

I used 91 once and it made the card pudgy but the 98 RON which i have used for the past 40k KMS is gold !! love it !

Lagom · 04-03-2006, 11:35 AM

Here's an interesting article on the matter - click here.

Off the top of my head, the best 0-100km/h results in the Fiesta were on 95RON, not 98RON - quite interesting really.

Ives · 28-05-2006, 09:36 AM

Anyone tried the Optimax Extreme? It's 100RON (+ 5% ethanol).

http://www.shell.com/home/Framework?...r_extreme.html

kenneth_lks · 28-05-2006, 05:32 PM

The benefit for 91RON is cheaper, but you probably have to change the oil filter earlier and affect the performance of that car. This is what the Ford Mechanic told me at the last 15K service. But I used only Optimax and Ultimate cause not too much different for a small car like that..

Hmmm, must try the Optmax Extreme..

Swaytan · 28-05-2006, 07:23 PM

Quote:

Originally Posted by Lagom

Here's an interesting article on the matter - click here.

Off the top of my head, the best 0-100km/h results in the Fiesta were on 95RON, not 98RON - quite interesting really.

That is quite interesting.

When I bought my Fez the salesman told me that it isn't really nessecary to use premium all the time, but did advise me that I should fill up on premium every 5th tank.

In saying that, I notice that running 95RON makes my Fez more responsive, especially when just starting it.

robjh80 · 28-05-2006, 09:20 PM

[QUOTE=kenneth_lks]The benefit for 91RON is cheaper,QUOTE]

Cheaper in the short term......at the bowser,...... but in the long term 91RON is basically a dirtier running fuel than the premium blends, can clog up your injectors a whole lot quicker resulting in the short term money savings going right out the window, not to mention a slight lack of performance using 91RON = "less driving fun", the premium 95RON and 98RON blends definately give most small cars a little extra zip, but of course not too much either, also not too noticable in a larger car ie: 6 Cylinder, but when you've only got 74kw under the bonnet, I guess every bit helps.......I only run mine on 98RON......a couple of extra bucks over 91RON when the petrol giants are screwing ya over anyway......what does it matter, we're all getting shafted any which way you look at it. :jab:

kenneth_lks · 28-05-2006, 09:34 PM

I agree with u...I used only 98Ron either

Ives · 28-05-2006, 10:21 PM

I just filled my car with Vortex 95RON, and it ran much smoother than the moment I drove out of the dealer (I guess they didnt put premium on the car). Performance-wise.. it's a lil bit more responsive, easier to get up to that 3000rpm zone (normal driving).

crispymk2 · 29-05-2006, 01:32 PM

I work at a servo and wouldn't put 91 (regular) in anything decent or built after 1990 full stop, tho i had a porsche put 91 in the other day, I could have slapped him...

The engine runs smoother and COLDER (lower intake temps = higher density air = more power + economy) with 95 and 98 but as mentioned most cars dont actually get much of a performance increase in going from 95 - 98. This is because it needs to be tuned for the higher octane and if the ECU cant adapt then the increase is minor.

by the way is 130km before moving off full normal?

Ives · 10-06-2006, 05:10 PM

I read somewhere on MOTOR magazine that some dude put in 98RON fuel from different brand (filling up a near-empty tank) and he noticed that his car wasnt performing as well as it did.

Is there any brands of 98RON fuel that you feel it's best for your Fiesta? I've been dumping in Vortex98 on mine.

Ives · 10-06-2006, 07:43 PM

^^^ How come I couldnt edit my own post? :(

I was just reading some stuff about petrol in the US. I think we're pretty lucky that our minimum octane level is 91. In the US, regular unleaded petrol is 87RON

"The most common levels of octane are 87 (regular), 89 (mid-grade) and 93 (premium). These levels are indicated on each gas pump at the station. Higher-octane gasoline can be helpful particularly for car engines that are experiencing knocking or pinging. However, octane is only one component to consider when shopping for fuel."

Their top of the line Shell "V-Power" (equivalent to Optimax) is only 93RON.

Lagom · 11-06-2006, 10:52 AM

Funny thing is, in the RACV's tests, 95RON had the best acceleration times

Ives · 11-06-2006, 11:21 AM

Yeah, that's interesting. But I find when I use 95RON, the car just SUCKS up the fuel. I get better milage using 98RON. (I'm not caining my car...)

Lagom · 11-06-2006, 11:54 AM

Quote:

Originally Posted by HyperKid

^^^ How come I couldnt edit my own post? :(

I was just reading some stuff about petrol in the US. I think we're pretty lucky that our minimum octane level is 91. In the US, regular unleaded petrol is 87RON

"The most common levels of octane are 87 (regular), 89 (mid-grade) and 93 (premium). These levels are indicated on each gas pump at the station. Higher-octane gasoline can be helpful particularly for car engines that are experiencing knocking or pinging. However, octane is only one component to consider when shopping for fuel."

Their top of the line Shell "V-Power" (equivalent to Optimax) is only 93RON.

That's incorrect - you can't directly compare US octane levels to Australian ones as they use MON, whereas we use RON.

US 87MON is slightly above our 91RON.

Ives · 11-06-2006, 12:22 PM

Ah, alrite.

Those people up there are living in their own world. Miles, gallons, feet, inches, yards, fahrenheit. :/

Ives · 16-06-2006, 07:42 PM

Anyone tried "Optimax Extreme" yet? 100RON + 5% ethanol... anyone?

MISTA FIESTA · 16-06-2006, 08:17 PM

Yeah I tried it, it seemed to be a better fuel, more response in throttle car ran smoother, but the fuel didnt last long.

Al... · 17-06-2006, 09:28 AM

i use it often.... as Mr Fiesta says, it does feel better overall , particually top end and freeway speeds fuel economy is about the same to me(550km/tank).but testing for performance gains will decrease eonomy, my first tank seemed to chew through it, second tank was back to normal

Ives · 17-06-2006, 02:20 PM

I see.

Al, your Fiesta is a manual isnt it? Mine's auto... so it drinks more than yours.

But I'm planning to try out the Optimax Extreme during the week... there's a shell near my work that's got one.

Al... · 17-06-2006, 11:17 PM

what i mean by the fuel consumption, is when ever something gets done thats supposed to give extra performace and also maybe able to give fuel savings, ie exhaust or airfilter etc, you tend to see how much better the car feels, but by driving hard, in that time the the economy goes down, but when u settle down again, the economy comes back to how it was or possibly better than before.