Fuel Octane rating

[MC]

I can see some of you don't understand what the octane rating is. Puring 98 isn't the best for every car. I'm not going to do the explanation here but I hope you find this useful:

So according to that, I should be using 95RON on my XR6T and 98 on the GT when or if it ever arrives. And 91 on the old Celica, as I do. When my dad was restoring the '67 Mustang (which is still at his place as I don't have garage space at present) he replaced the exhaust valve seats with harder ones so that it can happily run on 91RON without the lead additive doing the cushioning. Think something was also done to the head ... my engineering knowledge runs out pretty quickly. I just know it sounds really loud .

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[Rex Chan]

So I asked Ford Australia on fb and this was reply :

Hi Rex, thanks for your message. We can only comment on the Mustang that it sold here in Australia and that is recommended to use 98 octane unleaded in your Mustang though it has been optimized for operation using 95 octane unleaded. Your Mustang can operate using 91 octane unleaded, however as the manual states, it should be left for emergency only when neither 98 nor 95 aren’t available. Hope this helps. Thanks FordServiceAU^CZ

This lines up with user manual apparently (which i don't have) that it has been calibrated (by Ford powertrain engineers) to run on 95RON. Using 91RON may cause less power due to retarding spark to prevent knock. It won't damage your engine.

 

[Rex Chan]

@G_RUSH Why do you say Australia has shit fuel? Don't you trust the lab at the local refinery in WA to do their job? I trust mine here in Victoria to certify 95RON as 95RON.

Also, modern engines have knock sensors which will prevent any damage.

 

[Rex Chan]

[MENTION=14692]Aus-MustangGT[/MENTION] United buys on wholesale market i think whatever is cheap. BP Shell Caltex have longer agreements with the refineries but i still think its all the same base fuel 91/95/98RON. Just different additive packages at the distribution terminal. There are lots of threads on other firums about this arrangement.

 

[Burkey]

So I asked Ford Australia on fb and this was reply :

Hi Rex, thanks for your message. We can only comment on the Mustang that it sold here in Australia and that is recommended to use 98 octane unleaded in your Mustang though it has been optimized for operation using 95 octane unleaded. Your Mustang can operate using 91 octane unleaded, however as the manual states, it should be left for emergency only when neither 98 nor 95 aren’t available. Hope this helps. Thanks FordServiceAU^CZ

This lines up with user manual apparently (which i don't have) that it has been calibrated (by Ford powertrain engineers) to run on 95RON. Using 91RON may cause less power due to retarding spark to prevent knock. It won't damage your engine.

By "optimised" I think they're saying "yeah, you can run it, but your ignition timing is gonna retard when it starts to sense knock"
Which is not the same as saying "running on 95 is OPTIMAL"
That's my take.

 

[Rex Chan]

By "optimised" I think they're saying "yeah, you can run it, but your ignition timing is gonna retard when it starts to sense knock"
Which is not the same as saying "running on 95 is OPTIMAL"
That's my take.

The way that I read it, it actually says: the 5.0 GT is expecting 95RON, so by using 98RON, there will be no benefit.

Of course, if the sensors detect knock, they will retard.

But if the spark/cam timing is "optimised" (i.e. calibrated) for 95RON, then it probably won't care if you are running 98RON (i.e. it won't advance ign timing of cam phasing to make more power).

However, I don't calibrate OEM ecus, so I don't really know. I *did* however dyno tune using MoTeC M4/48/400 using E85 for a few years a while back, so I'm not clueless when it comes to engine calibration. And by dynotune, I mean a steady-state engine dyno, not these rolling road things tuners use.

 

[Burkey]

The way that I read it, it actually says: the 5.0 GT is expecting 95RON, so by using 98RON, there will be no benefit.

Of course, if the sensors detect knock, they will retard.

But if the spark/cam timing is "optimised" (i.e. calibrated) for 95RON, then it probably won't care if you are running 98RON (i.e. it won't advance ign timing of cam phasing to make more power).

However, I don't calibrate OEM ecus, so I don't really know. I *did* however dyno tune using MoTeC M4/48/400 using E85 for a few years a while back, so I'm not clueless when it comes to engine calibration. And by dynotune, I mean a steady-state engine dyno, not these rolling road things tuners use.

I don't know either mate.
But I reckon the marketing team sometimes get a bit creative in their use of the English language.
Anyone who's actually tuned an Aus spec car should be able to tell us what they've seen. Having said that, if I was taking my car in for a flash tune I don't reckon it'd have a tank of 95 in it somehow... :shrug:

 

[MC]

The way that I read it, it actually says: the 5.0 GT is expecting 95RON, so by using 98RON, there will be no benefit.

Of course, if the sensors detect knock, they will retard.

But if the spark/cam timing is "optimised" (i.e. calibrated) for 95RON, then it probably won't care if you are running 98RON (i.e. it won't advance ign timing of cam phasing to make more power).

I think they don't know what optimized means. The key word for me is recommended. I will be sticking with that until proven otherwise. So I think they mean 98RON is optimal, and that you can use 95 with no real issues as the knock sensors will take care of things, whereas 91 will get you there, but with noticeable loss of performance.

 

[4stanger]

Photo of page from my owners manual, from my Australian delivered Mustang, page 98, under the title "fuel quality".
Mine is an EcoBoost, however I don't think Ford would go to the extra expense to have 2 different owners manuals (GT & EcoBoost) for Australian delivered Mustangs at the time, as they did think early on demand would be minimal for this car :lol:.
Note the comment re- "using 91 octane", It states "The engine in your vehicle can also operate using 91 octane unleaded gasoline"
That there states, from Ford, the vehicle CAN use 91, it does go on to say about increase engine noise (that's good isn't it? no need to do muffler mods :lol and minor loss of engine performance (if you are going to race the car, don't use it). NO WHERE does it state there are warranty issues using 91. The only area it states warranty engine issues is the first note below in the photo, where it states using ethanol blends of more than 10%

 

[Burkey]

Photo of page from my owners manual, from my Australian delivered Mustang, page 98, under the title "fuel quality".
Mine is an EcoBoost, however I don't think Ford would go to the extra expense to have 2 different owners manuals (GT & EcoBoost) for Australian delivered Mustangs at the time, as they did think early on demand would be minimal for this car :lol:.
Note the comment re- "using 91 octane", It states "The engine in your vehicle can also operate using 91 octane unleaded gasoline"
That there states, from Ford, the vehicle CAN use 91, it does go on to say about increase engine noise (that's good isn't it? no need to do muffler mods :lol and minor loss of engine performance (if you are going to race the car, don't use it). NO WHERE does it state there are warranty issues using 91. The only area it states warranty engine issues is the first note below in the photo, where it states using ethanol blends of more than 10%

Totally off topic, but has anyone else noticed how bad the paper quality of the manual is?
Sorry, just had to mention it.

 

[quick duck]

I wonder why we are told not to use e85, yet other countries do.

 

[Rex Chan]

I wonder why we are told not to use e85, yet other countries do.

Probably because you need a flex-fuel sensor to monitor how much ethanol is in the fuel.


Anyway, I found an online manual from Ford AU here:

http://www.fordservicecontent.com/F...Owners-Manual-version-1_om_EN-AUS_07_2015.pdf


Text reads on page 98:

Note: We recommend that you use only
high quality fuel.

Note: We do not recommend the use of
additional additives or other engine
treatments for normal vehicle use.
E207795

Use minimum 91 RON octane unleaded
gasoline that meets the specification
defined by EN 228 or the equivalent
national specification.

Your vehicle is suitable for use with ethanol
blends up to 10% (E5 and E10).

 

[Frostee]

All I use is 98 RON from day 1

 

[Liber]

All I use is 98 RON from day 1

Me too. Why cheap out a few cents?

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