Octane Question

pkpilot · Apr 20, 2017

AlanColes said:
I'm sure that's exactly what's being done Marc. The manual specifies 93 RON for some BMW engines (European rating - an older system with flaws) which is 89 AKI (North American rating - a better method of classification). I have never seen any volume produced car or motorcycle in NA specify 93-AKI. The RTW calls for 95-RON which is 91-AKI.

This is starting to look too much like a bad oil thread.

Please remember, a little knowledge can be a dangerous thing, and, just because someone else said something or wrote something on the internet does not make it so. Also, do not think that what applies to generalized statements cars can blindly be applied to the specific requirements of motorcycle engines.

Unfortunately, far too many folks with too little depth of understanding on these matters are willing to provide pearls of wisdom and confuse matters significantly.

First, without sufficient information from BMW engineers or running detailed tests on these specific engines, we can only go by what information we do have from BMW and what is KNOWN about octane and engine management.

So, let us look at what BMW has published. BMW specifies that their maximum HP rating for the R1200RTW is achieved using 95-RON which is 91-AKI and that is the fuel they suggest. If we were talking about the previous generation 1200 (1170cc) engine, than things are different. IN that situation BMW provide two RON grades 95 and 98 (AKI 89 and 91) and identify that maximum HP is obtained using 91 AKI (98-RON).

That absolutely does not mean that the R1200RTW will produce any more or less HP with anything higher than 91-AKI. In fact it would indicate (not state, but indicate) that there would be no gain, otherwise, BMW would have followed their existing practice of identifying this.

Will the R1200RTW run on 89-AKI? Yes.

However, it will not run as optimally designed. The ability to operated in an acceptable manner on 89-AKI is a compromise due to poor fuel quality standards in the US and elsewhere. For some markets BMW used to specifically de-tune engines ECU (different mapping, part #, etc.) so they'd run on the typically inferior quality gas prevalent in those areas.

Will doing so provide any benefit whatsoever? Unlikely and you may reduce your long-term relaibiliy if you keep the bike.

The 3% (approx) cost savings between the two grades of fuel has as much or more to do with the differences in the "Additive Package" to the different fuel grades as it does with the octane difference. So, even if the lost of fuel economy by running 89-AKI is say 2% (I don't know the actual figure, but do know that it will exist) than there is a 1% savings in cost per mile ridden for the fuel expenditure, but, through that running/savings there has been an inferior additive package being used that in most cases is not as effective at reducing/ removing carbon deposits, gunk and wear. For instance, Shell's 91-AKI, V-Power NiTRO+ Premium Gasoline (which I use when practicle), "removes an average of 60% of performance-robbing gunk on intake valves left behind by lower quality premium gasolines".

Does a higher compression ratio require a higher octane fuel? No, not necessarily. The better the combustion chamber design is the lower octane it can run without any lose of power, fuel-economy, etc. I have seen engines with CRs of 9:1 that required 91-AKI to avoid detonation and others like my R1200RTW that have a 12:1 CR and are optimized to run on 91-AKI. It is a matter of design, and can not be blindly referenced from unrelated writings about any other engine.

As an aside, one of the reasons I run Shell V-Power is that indepentently of each other, I have had two top motorcycle engine builders (multiple National Championship winning) tell me that they tuned street bikes using Shell V-Power exclusively as they found their motorcycle engines made 1-2 HP consistantly using it vs any other readily available pump gas. YMMV

Just so you know, whenever I buy a vehicle from someone, I casually ask them what fuel the vehicle takes. If they admit that they run a below spec grade, I automatically reduce my maxium I'm willing to pay for it due to the "possibility" of issues. It isn't worth the possible 1% fuel cost saving only to end up with a top-end valve job perhaps 10% sooner - that is far more expensive. Would that happen? I don't know anymore than much of the unfounded speculation that has been posted here on the benefits running a "permissible but below recommended" octane for extended periods of time in this specific engine.

I do know that there is far more difference between Top-tier 91-AKI and 89-AKI than just the octane rating and not taking that into consideration has it's own costs. For me, I run what the manual states. Now oil is a different beast, anyone want to go down that worm-hole?

Only partially done the worm hole... First, there is no direct correlation between AKI and RON. AKI is actually a combination of methods averaged. Second, just because a station carries some "branded" gas does not mean you are getting that gas. Watch gas stations when they are getting filled. Look at where the tanker trucks are coming from, then where they go. You cannot be sure of what you are actually getting. We won't even get into the mixing of fuels on the trucks, and the slightest contamination can have significant effects on the actual RON/ROZ/ROM/AKI of the fuel. Distribution, at least is the US, is fairly centralized by region. Lots of mixing going on outside the sight of the consumer.

Sent from my iPad using Tapatalk

marcopolo · Apr 20, 2017

Alan, you've confused me. The manual for my 2015 GSA clearly recommends 89 AKI. And, from the scan of the RT's manual (see post above), the RT's manual recommends exactly the same grade fuel, i.e., 89 AKI. You seem to be saying that these bikes are designed to use 91 AKI. Did I read your post correctly? If so, why would you recommend a fuel grade other than what BMW recommends in the relevant manual for these bikes? Have you simply converted from 95 RON and arrived at 91 AKI, as opposed to the 89 AKI spelled out in the manuals?

AKsuited · Apr 20, 2017

That scan of the manual is confusing - "Super Unleaded" to me means one level above 89...

Harry

jaflowers · Apr 20, 2017

I find it a little odd that some here, who have spent roughly $20,000 on these incredible machines, are a bit "cheap" about filling up their fuel tank. I know money adds up over time but for an extra $.25 cents a gallon on a 6 gallon fill up you're spending a whopping $1.50 extra on premium gas......I just don't see the big deal. You've already bought what most of us consider to be the absolute top of the line and damn sure expensive bike so you've got a few bucks to your name...what's a $1.50 in the scheme of things??

As an aside, I always use premium and out here in Colorado it's only 91. Sure wish I had a close by store with pure gas as that'd be my mainstay if I could.

marcopolo · Apr 20, 2017

AKsuited said:
That scan of the manual is confusing - "Super Unleaded" to me means one level above 89...

Harry

Depends where you go. I generally use Exxon, and there they label 87 as "Exxon regular", 89 as "Exxon Plus", and 91-93 as "Exxon Supreme". To me, super unleaded could mean anything above regular.

pglaves · Apr 20, 2017

marcopolo said:
Depends where you go. I generally use Exxon, and there they label 87 as "Exxon regular", 89 as "Exxon Plus", and 91-93 as "Exxon Supreme". To me, super unleaded could mean anything above regular.

The numbers matter. The labels the marketers use to entice us are generally less than useful and sometimes deliberately misleading.

alancoles · Apr 20, 2017

pkpilot said:
... First, there is no direct correlation between AKI and RON. AKI is actually a combination of methods averaged. Second, just because a station carries some "branded" gas does not mean you are getting that gas. Watch gas stations when they are getting filled. Look at where the tanker trucks are coming from, then where they go. You cannot be sure of what you are actually getting. We won't even get into the mixing of fuels on the trucks, and the slightest contamination can have significant effects on the actual RON/ROZ/ROM/AKI of the fuel. Distribution, at least is the US, is fairly centralized by region. Lots of mixing going on outside the sight of the consumer.

Sent from my iPad using Tapatalk

Just a slight correction to what was likely a mistype (I have a terrible time some days):

pkpilot said:
... RON/ROZ/ROM/AKI ...

ROZ is just the German term for RON and I suspect you meant MON rather than ROM.

You're quite right, AKI is (RON+MON)/2. There are three different main indexes used RON, MON, and AKI. The gasoline itself typically comes from a very few refineries and is transported via truck to many different gas station brands. One or two sources for the base and each Brand (Shell, Mobil, etc.) then use their own proprietary Addative Package, just as with oil. I beleive this is done at the pump somewhere between the underground tanks and the pump nozzle.

As for what one actually gets at the nozzle, that is controlled by the honesty of the gas station, it's parent company, and the voracity their oversight as well as that of the government bodies that police it and we should perhaps, just say that nothing is perfect.

Marc, I confuse myself as well. ;-)

I believe that BMW may have made a mistake in their manual or in its translation (although translation issues shouldn't have caused that).

We've got too many standards to deal with and very poor cross-correlation, unfortunately. I wish countries could decide on a "Best Practices" or ISO preferred standard and we'd be done with this. There even appears to be differences between AKI conversions depending on who you read or talk to.

My BMW Riders Manual states 95-RON or 89-AKI, which did not seem right to me. My understanding of things was that in North America 95-RON was 91-AKI. The accepted rule of thumb is that the RON of a gasoline equals the AKI + 4 to 5, and that equates to 95-RON = 91-AKI.

So I called Shell Oil's technicial division and spoke with one of their engineers. He actually worked out the calculations over the phone with me and identified that, contrary to what BMW states in thei Riders Manual, 95-RON is equivalent to 91-AKI in Canada and the US. For their V-Power the 95-RON comes to something like 90.8-AKI (91).

Here's some reading if you want to get crazy on the stuff: http://www.chevronwithtechron.ca/products/documents/69083_MotorGas_Tech_Review.pdf

There is more detailed stuff available, but when I ran across the discepency I didn't wan to spend the $65 USD for it and just talked with a gasoline engineer instead.

motodan · Apr 20, 2017

EVERYONE STOP! Now at least one of these experts post your degree(s) in petroleum engineering so we can decide who MIGHT have more than a home read acumen in what they type. Otherwise pick a number and go for it....

AKsuited · Apr 20, 2017

From that Chevron pdf:

Generally, three grades of unleaded gasoline with different AKIs are available in the U.S.: regular, midgrade, and premium. At sea level, the posted AKI for regular grade is usually 87; for midgrade, 89. The AKI of premium grade varies, ranging from 91 to 94.

As I said before, "Super unleaded" (the wording in the BMW owner's manual) means "Premium" to me, it doesn't mean "midgrade." Am I wrong? The owner's manual for my GS says the same thing as the RT manual...and also says that "89 AKI" is okay. So which is it, BMW, 89 AKI, or Super unleaded? Semantics, yes, but the issue is still subject to debate.

If you pulled your car into a full-service gas station and told the attendant to fill it up with "Super," I would expect him to put in AKI 91 (or higher) and not the midgrade. YMMV.

I'll keep using Premium in my 2015 R1200GS.

Harry

kioolt · Apr 20, 2017

The use of the AKI rating is most likely government regulated. I doubt the use of the words super or premium when talking about gas are.

motodan · Apr 21, 2017

LFarling said:
Reading comprehension here folks.

As I said this is a list. Preferred, second choice, third choice.

I mean even when you see it in Black and White you want to argue over it.

Super unleaded is what the preferred recommended gas for the LC RT is. In PA we consider Super unleaded 93. We have 87,89,91,93 at most stations.

You can try and justify using 87 or 89 but you are just mind bumping yourself.

Insane so many would try and justify using swag gas in a motor made to run on Super unleaded.

You mean "black and white" like this forum thread? Of course I note you are typing on behalf of "we" people of PA...that elected or appointed?

marcopolo · Apr 21, 2017

LFarling said:
Reading comprehension here folks.

As I said this is a list. Preferred, second choice, third choice.

I mean even when you see it in Black and White you want to argue over it.

Super unleaded is what the preferred recommended gas for the LC RT is. In PA we consider Super unleaded 93. We have 87,89,91,93 at most stations.

You can try and justify using 87 or 89 but you are just mind bumping yourself.

Insane so many would try and justify using swag gas in a motor made to run on Super unleaded.

I don't agree with your conclusion. No way I think that that's a list of three recommended fuel grades, as you seem to imply. Also, I don't think anyone is trying to justify anything, other than using the fuel BMW recommends.

My 2015 GSA manual has two boxes that talk about recommended fuel.

Here's the first:

"Recommended Fuel Quality

Super unleaded (max. 10 % ethanol, E10)
89 AKI (95 ROZ/RON)
89 AKI"

Here's the second:

"Alternative Fuel Quality

Regular unleaded (restrictions with regard to power and fuel consumption.
If the engine should for example be operated with 91 RON in countries with lower fuel quality,
the motorcycle must be respectively programmed first by your authorized BMW Motorrad retailer.) (max. 10 % ethanol, E10)
87 AKI (91 ROZ/RON) 87 AKI"

Seems pretty clear to me that the recommended grade is 89 AKI, but that you could use regular 87 AKI, if you first have your bike reprogrammed by a dealer. Also, as I said earlier, my dealer took great pains to point out, when I took delivery, that the recommended fuel grade was now 89, as opposed to the 91 that was recommended for my 2006 RT. The RT called for "Super Plus Premium, 98 ROZ".

In the end, of course, put anything in the bike you want. It's your bike. I just don't think it's in any way unclear in BMW's documentation. And, despite what's been written in this thread, I would find it hard to believe that BMW could have erred in thousands of manuals for a variety of new boxer models.

jrgator · Apr 21, 2017

On a side note, I typically use 93 non-ethanol. If that's not available, 93 with no more than 10% ethanol. Can't imagine that I would consider 87, or even 89 for that matter.

pglaves · Apr 21, 2017

jrgator said:
On a side note, I typically use 93 non-ethanol. If that's not available, 93 with no more than 10% ethanol. Can't imagine that I would consider 87, or even 89 for that matter.

OK, that is what you do and think, but what precisely does BMW specify for your model?

alancoles · Apr 21, 2017

Motodan said:
EVERYONE STOP! Now at least one of these experts post your degree(s) in petroleum engineering so we can decide who MIGHT have more than a home read acumen in what they type. Otherwise pick a number and go for it....

No need to shout Dan.

I don't feel that an engineering degree is required to deal with most of what is being discussed here - What AKI rating is BMW actually referring to in their literature, but I did speak to one and did report their input which supported my understanding of things..

The issue is more one of too much misinformation running rampant, in addition to people making statements without sufficient depth of knowledge/understanding/experience of the field.

If we had a better-standardised reporting of AKI ratings vs RON or if BMW were contacted to clarify then there'd be very little issue. RON vs AKI can be misleading because it isn't really an exact conversion, but, one must use a conversion to address the two with respect to each other.

Unfortunately, you can find dozens of RON to AKI conversions that say different things and that is why, some time ago, I contacted Shell's Technical Department and spoke with one of their Petroleum Engineers and reported their response to the question of "What Shell AKI rating should I use if the manual specifies 95-RON." The response was 91-AKI. I asked about their Shell V-Power Nitro+ 99 that I see in Scotland and England (99-RON) and he stated that it tests out at 93-AKI.

It only takes common sense to identify that it appears BMW perhaps made a mistake in the manual. If you look at the BMW Motorrad site for both the US and Canada (as I did when the RTW was introduced), you would see that in the US the Site calls for using "Premium" fuel (no one will argue that that isn't 91-AKI or higher). In Canada it calls for "Unleaded super, octane number 95 (RON)", which is known here to be 91-AKI.

If you consider that for their new Limited Edition 2017 HP4 Racer BMW specify "Superplus unleaded petrol, minimum octane number 98 (RON)" for Canada and the Canadian fuel that is stated to be 93-AKI and 94-AKI is identified as 98-RON than, guess what - 95-RON should = 91-AKI.

In Europe (Germany in particular) fuel I've seen at the pumps that is referred to as SuperPlus is 98-RON, and fuel labelled just Super (not SuperPLus) is 95-RON. If you look at the nomniculture used to describe them these all fall into place properly, however, when trying to identify them by other means things get extremely confused, and that's where the problems begin.

I have used the table in the following for many years: http://www.pencilgeek.org/2009/05/octane-rating-conversions.html

You can also use this: https://en.wikipedia.org/wiki/Octane_rating

In a nutshell, what all that gives you is:

---RON-to-AKI---
98-RON = 93-AKI - SuperPremium or SuperPLus
95-RON = 91-AKI - Super or Premium
93-RON = 89-AKI - Mid-grade
90-RON = 87-AKI - Regular
These descriptive terms align "generally" across both what I've seen in Europe (RON) and in North America (AKI) when matched up like this but only irregularily (hence the confusion), if aligned in any othe manner.

For me, the biggest problem is having two standards when looking at a manual, it would be much preferable to use just one. The RON standard has very little to do with if a fuel will get into detonation in a car or motorcycle in the real world, this is where AKI does a much better (still imperfect) job.

YMMV

alancoles · Apr 21, 2017

PGlaves said:
OK, that is what you do and think, but what precisely does BMW specify for your model?

Paul, I do believe that is part of the problem. BMW in many places specifies "95-RON or 89-AKI" as being equivalent.

It is my understanding that 95-RON = 91-AKI. I think that when being translated they messed up and used the "minimum" permissible AKI (89) when they were rferring to the "recommended" AKI which I believe to be 91-AKI.

AKsuited · Apr 21, 2017

PGlaves said:
OK, that is what you do and think, but what precisely does BMW specify for your model?

I'll add to what Alan Coles has offered. BMW's advice is anything but precise. Some results of Googling follow:

https://www.exxon.com/en/octane-rating

The octane ratings of Exxon and Mobil gasoline
• Exxon and Mobil Regular Unleaded Octane 87
• Exxon Plus and Mobil Special Unleaded Octane 89
• Exxon Supreme and Mobil Super+ Unleaded Octane 91-93

https://en.wikipedia.org/wiki/Gasoline
In the UK, ordinary regular unleaded gasoline is 95 RON (commonly available), premium unleaded gasoline is always 97 RON, and super unleaded is usually 97–98 RON.
In the US, octane ratings in unleaded fuels can vary between 85[16] and 87 AKI (91–92 RON) for regular, through 89–90 AKI (94–95 RON) for mid-grade (equivalent to European regular), up to 90–94 AKI (95–99 RON) for premium (European premium).

https://myweego.com/2015/12/08/regular-premium-super-gasoline-what-type-of-fuel-should-you-use/
You see the numbers every time you fill up your tank – Regular fuel is always associated with 87. Premium fuel is typically rated at 91, and Super is usually rated at 93. Those numbers are actually telling you how much octane is in that fuel: 87% octane for your Regular gasoline; 91% octane for Premium, and 93% for Super.

http://www.businessinsider.com/what-is-premium-gas-2012-9
In Europe, the octane rating on the pump is simply the RON figure. America, by contrast, uses the average of the RON and the MON figures, called the AKI (anti-knock index). Thus, 97 octane “super unleaded” in Britain is roughly equivalent to 91 octane premium in the United States.

http://wikicars.org/en/Octane_rating
Germany, "Normal" 91 RON, "Super" 95 RON and "Super Plus" 98 RON is practically available everywhere. Big suppliers like Shell or Aral offer 100 RON gasoline (Shell V-Power, Aral Ultimate) at almost every fuel station. "Normal" 91 RON is more and more disappearing, because lower production amounts make it more expensive than "Super" 95 RON, so it is often not offered any more.
United Kingdom, 'regular' petrol has an octane rating of 95 RON, with 97 RON fuel being widely available as the Super Unleaded.

Generally, octane ratings are higher in Europe than they are in North America and most other parts of the world. This is especially true when comparing the lowest available octane level in each country. In many parts of Europe, 95 RON (90-91 AKI) is the minimum available standard, with 97/98 RON being higher specification (being called Super Unleaded).

Besides any confusion caused by RON/MON/AKI numbers, there is also the differences among locations as to what exactly "Super Unleaded" means.

I recall using 89 AKI in my '03 RT and noticing that with 91 AKI, the bike ran smoother.

There is also the possibility that the owner's manual may have been written for the UK, and then borrowed for the US and Canada, a possible source of the imprecise usage of the term "Super Unleaded."

Harry

roadancer · Apr 21, 2017

E-0

We have E-0 ,91 as a tier one fuel in the area. The difference in performance is quite noticeable . Not just in raw power, but in starting, idling, roll-on, and mileage. The same characteristics apply on our performance 2X snowmobiles. When on tour, if not available, we run 91 tier 1 and polish it with a trace of upper cyl. lube. The most important is who bought what fuel before you. If the car before you bought 87 and you pull up, your going to get around 2 gal. of 87 before you get what you thought. So there's wisdom in going higher than book as dilution could be a factor. Best bet is 91 E-0 as it usually is in a non select pump.

t6pilot · Apr 21, 2017

roadancer said:
We have E-0 ,91 as a tier one fuel in the area. The difference in performance is quite noticeable . Not just in raw power, but in starting, idling, roll-on, and mileage. The same characteristics apply on our performance 2X snowmobiles. When on tour, if not available, we run 91 tier 1 and polish it with a trace of upper cyl. lube. The most important is who bought what fuel before you. If the car before you bought 87 and you pull up, your going to get around 2 gal. of 87 before you get what you thought. So there's wisdom in going higher than book as dilution could be a factor. Best bet is 91 E-0 as it usually is in a non select pump.

The question of what's left in the pump line from previous user has been asked here in California many times. The people who monitor the pumps, weights and measures, say less than a pint gets mixed
As to the octane of the gas you use, pick one, if your happy with it, use it
My bike seems to like chevron premium the best
I tend to stay away from no name stations, scares me what concoction they may put in the gas

36654 · Apr 21, 2017

LFarling said:
Your bikes do as you please for sure.

If you can not RTFM right, and interpret a listing, as use of any of these in this order, (starting with Super unleaded) then shame on you.

If the listing was the other way around in order would it make sense to you?

As far a "We" in PA yes I should have said I however it does not change the fact Super unleaded is 93. Or that We(as all people who live in PA) have access to 87,89,91,93 gas. If you tell a gas jockey you want Super unleaded you are getting 93. Premium unleaded would get you 91.

I am out on this like I said your bikes run what you want in it. Read a listing of preferred requirements, in descending order, and say it is not a listing is fine with me. Got nothing invested in your bike.

https://www.exxon.com/en/unleaded-gasoline

"We" in PA? This is getting good.

The book, from the manuafacturer, says 89 AKI. That's good enough for this "we" in PA

Octane Question

New member

Active member

New member

New member

Active member

#13338

Dress for fall & avoid it

Active member

New member

New member

Active member

Active member

New member

#13338

Dress for fall & avoid it

Dress for fall & avoid it

New member

New member

Active member

New member

Similar threads