What grade gasoline are you using?

[CycleRob]

WhoZat = Pat? E-Mail me and catch up.

This fuel grade poll stirred up quite an info-fest. Seeing the results, I was surprised at the high % of Premium users (the top grade). Even the low turnover stale gas issue was well covered. An 8 month old Premium grade fuel is prolly worse than a fresh Regular grade fuel.

The higher octane fuels are obtained by adding additives to Regular grade fuel that slow down the fuel mixture's burn rate. After a rumor that Regular 87 octane makes more HP than Premium grade gasoline an adventurous racer with a 1998 Kawasaki ZX-6R decided to try it. We Dyno tested it on both gasoline grades over a few day period and sure enough, the Regular gas made a little under 2 more HP. Also really surprising is that we detected no pinging. He said it didn't ping on the road either. Conclusion: Regular grade (87) gasoline gives the best power & fuel economy.

Here in Gainesville Georgia (USA) the cheapest Premium is $3.69/Gallon. Check it out HERE. On that map, my house is North of route 53 in the 11 O'Clock portion of the map. For more info, scroll all the way to the screen bottom. If you are curios about gas prices, just change the ZIPcode in the white box on the upper right of the map.

[def38]

An octane of 98 is required but I mostly use Shell V-Power, which has an octane of 97 in the Netherlands.
Sometimes 98 and very sometimes (rarely) 95.
It is expensive anyway, so therefor I'd rather use the best for my "baby"

In the Netherlands the price of V-Power 97 is € 1,65 /liter = $ 2,43 /liter = $ 9,20 /US gallon
I remember 15 years ago when I was in the States a US gallon gasoline costed me $ 1,27 /gallon (by the way do you still count in gallons???)
How much is it nowadays?

US Gallons are still the unit of measure for many of our liquids including gasoline, diesel fuel, milk, water, etc.

As you are aware, the recent hurricane which made landfall in Galveston, Texas required the evacuation of oil platforms as well as local refineries. As a result, fuel costs in much of the US have skyrocketed once again to $4.00/US Gallon in spite of the fact that crude oil futures have been falling consistently and are currently below $100.00/bbl. RBOB gasoline is at $240.00. There should be regulation of the refiners and oil companies. They, along with the market speculators, are causing record gasoline prices. Ridiculous!

[Bheckel169]

This is hearsay only but I was told by a reliable source that a supplier of gasoline told them that basically the high octane and the plus octane gas is the same. They just fill up the high octane tank at the station and use the same gas to fill up the tank for the middle grade. I have tried using the middle grade and have not noticed any pinging or lack of performance.

[NAIAD]

Bheckel169,
Some brands do use a "mixing pump" that pulls a proportion of regular and supreme from those storage tanks to provide a mid grade fuel. At least some used to do that. Depends on what state you live in, but most states have regulatory divisions (usually Weights and Measures) that not only test volume of gas from each pump, but also test octane. Most (if not all) major brands these days do distill a mid grade fuel and use that to fill the local storage tank. FWIW, I used to drive a tanker for ARCO, so I've been down that road before.

And this is not a opinion by an ARCO person...I only use Chevron!

And only premium in my machine at sea level...

Cheers! BJ

[winkeldc]

Now I have a question. The poll shows that most put the premium stuff in the bike, but how does that translate to MPG. All this talk about what is used doesn't help unless we have some performance benchmarks to measure with. I use the premium stuff, but my commute is mostly city streets under 35 mph. I get about 43 mpg, unless the gas is "stale" which I may have just experienced and then it went down to 40 mpg. Are the guys using mid grade or lower seeing the same mpg (or equivalent)?

[def38]

WhoZat = Pat? E-Mail me and catch up. The higher octane fuels are obtained by adding additives to Regular grade fuel that slow down the fuel mixture's burn rate.

Sorry...not correct.

Gasoline road fuel is blended, refined, cracked or hydrocracked to provide various levels of anti-knock capability which is determined using the ASTM MON+RON/2 test method. Variables such as compression ratio, stoichiometry,
combustion chamber shape, fuel composition, number and position of spark plugs, turbulence etc. determine anti-knock requirements. Burn rate has no correlation to anti-knock properties. Fuel octane rating is a function of the heptane to octane ratio of the fuel blend.

Knock or detonation occurs when cylinder pressure and temperature increase to levels which cause autoignition and secondary combustion fronts elsewhere in the combustion chamber. These uncontrolled, unwanted secondary flame fronts cause a very rapid rise in combustion chamber pressure along with secondary chemical reactions in the resident air/fuel mixture.

The result is rapid temperature increase along with extreme pressure increase and the ping or metallic knock we here when detonation takes place. If left unabated, detonation can lead to engine damage in the form of cracked cylinders, burned pistons, warped or broken valves, overheated engine oil and destruction of the Nikasil cylinder wall surface.

Those of you with knock sensors in your engine management system are fortunate in that the knock sensor can help eliminate engine damage due to low anti-knock fuel rating (octane) or poor fueling. My oilhead ('01 GS model) does not have such a system and as such, I must be mindful of detonation and adjust my throttle setting at the onset of audible knock or risk engine damage.

[def38]

Now I have a question. The poll shows that most put the premium stuff in the bike, but how does that translate to MPG. All this talk about what is used doesn't help unless we have some performance benchmarks to measure with. I use the premium stuff, but my commute is mostly city streets under 35 mph. I get about 43 mpg, unless the gas is "stale" which I may have just experienced and then it went down to 40 mpg. Are the guys using mid grade or lower seeing the same mpg (or equivalent)?

Engines have an octane rating requirement determined by those who designed and tested the engine. The octane requirement changes with temperature, barometric pressure, humidity, altitude and the state of tune of your engine. Fueling with higher-than-required octane fuel will NOT provide increased power or performance. It will only waste your money. Refer to your MOM and follow the fuel octane requirements shown therein.

The stale fuel you refer to is fuel which is old enough that the oxygenates have degraded to a different chemical state...very undesirable. Also, the fuel may be so old as to have begun to form gum residues. Stale fuel has a characteristic odor which is readily discernible.

I trust truck stops. Typically they maintain their tanks and pumps and dispense fresh fuel of correct grade. If you are in doubt about a station, ASK! Ask the attendant when they received fuel last and from what distributor. If they don't know, go elsewhere.

Avoid stations that do not turn over fuel frequently.

[def38]

This is hearsay only but I was told by a reliable source that a supplier of gasoline told them that basically the high octane and the plus octane gas is the same. They just fill up the high octane tank at the station and use the same gas to fill up the tank for the middle grade. I have tried using the middle grade and have not noticed any pinging or lack of performance.

Mid grade fuel is blended in the pump, taken from the two tanks underground at the station. There are few remaining modern stations with three underground tanks.

[def38]

Lower grade fuels also tend to have more particulates that can cause fuel system issues especially if you don't run your tank to empty occasionally.

What? I have never heard of this. What is your source for this information?

[deilenberger]

Now I have a question. The poll shows that most put the premium stuff in the bike, but how does that translate to MPG. All this talk about what is used doesn't help unless we have some performance benchmarks to measure with. I use the premium stuff, but my commute is mostly city streets under 35 mph. I get about 43 mpg, unless the gas is "stale" which I may have just experienced and then it went down to 40 mpg. Are the guys using mid grade or lower seeing the same mpg (or equivalent)?

Dunno - never used it. FWIW - my last tank of fuel surprised me. The MPG readout gave me 46MPG, which is sorta average on my bike (rarely under 43, rarely indicates above 50). When I calculated the MPG myself via the odometer reading and the fuel used - it was 56 MPG, the best I've ever gotten.

[NeilS]

Fuel octane rating is a function of the heptane to octane ratio of the fuel blend.

I disagree. That was the original definition of octane rating, actually the ratio of iso-octane to (iso-octane + n-heptane). But gasoline these days is so much more than just a mix of heptane and octane. Octane rating can be improved by both the basic chemistry of the fuel and the use of additives. For example, when tetraethyl lead was legal, you could increase the octane rating of a fuel to almost any arbitrary point just by adding enough lead.

Burn rate has no correlation to anti-knock properties.

The fact that the ECU can control knock by retarding the timing suggests that this isn't true. Ignition advance is intended to compensate for the burn rate of the fuel. In other words, you want to start the fire enough in advance of TDC so the pressure wave created by the combustion reaches the piston just after TDC. A slow-burning fuel needs a lot of advance and vice-versa. If the fuel's burn rate is so great that the pressure wave reaches the piston before TDC, you get a knock; then the ECU reduces the advance to correct the condition.

FWIW.

[Bheckel169]

Don,
Interesting point and I concur. Based on my computer, I was getting about 45 mpg. When I calculated actual fuel pumped versus my odometer reading for my tank I found I was getting 55 mpg. Quite a difference and seems to match up with the number of miles my computer says I'm able to get before I run out.
Bruce

[Phillo]

The only petrol or gas as you guys call it that we can use here on the coast is 95octane ULP and I get on average 55mpg.

[famousperson]

The only petrol or gas as you guys call it that we can use here on the coast is 95octane ULP and I get on average 55mpg.

Do you guys use US or Imperial gallons?

[Phillo]

We actually use litres and usually calculate our consumption as litres per 100 km but given that you guys were talking gallons I based the calculation on an Imperial gallon or 4.5462 litres and converted km to miles.

[Enjoy-Rider]

Oops....... I assumed that in the US they calculate with US Gallons which is 3,785 litres

[webmost]

I read thru this whole thread and was astonished that no one yet pointed out that:

a) European octane is apples. American is oranges. The diff is the American is tested at operating temperatures as well as under cold lab conditions. The American octane rating is an average of the two methods. That average is generally 5 or 6 points below the Euro. So 95 octane Euro is just about mid grade American 89 octane.

b) Ethanol raises octane too; not just because there's so much less energy in it, not just because it burns slower, but also because the longer it sits in the tank the more water it absorbs. Water doesn't burn real readily, or so says the local firehouse, which uses it to douse flames. So stale gasohol bites. Especially in Winter. Therefore, mileage tests and such will vary widely according to weather and the source of gas. As well as, of course, driving habits. We can only get gasohol here in Dull-Aware.

c) It's flat impossible to compute accurate miles per gallon on a single tank, because it's flat impossible to refill your tank to exactly the same level as you did last time. You really need to keep records on a nice long thousand mile trip and average out.

d) More octane is not more power. Octane measures how quick the stuff pops; not how big it bangs. Your best power will be where it pops at the right rate for the way your engine goes round. It's cams and compression matched to octane that does the trick. If anything, ever additive used to raise octane only displaces the stuff that makes power. So more octane is less power.

However, all these discussions get nowhere. There is a substantial number of people who are firmly convinced that more money equals more better regardless the topic. They are never budged off that conviction no matter what facts are presented. That's why service stations can charge eighty cents more for premium, despite the fact so many sources agree that no stock auto engines made in the last 20 years require it. "Money doesn't matter to me!" they brag. That's not the point. More money is not always more better. The right grade for the engine is the deal.

I have not gone but one long ride on my Roadster, and that was only 450 miles; so I can't say what mileage she gets. I suspect about 50 on the road; far less in town. I have done numerous tests on my R1200CLC, however. In one, for instance, I rode 1000+ miles to Indiana using regular 89 octane all the way, into a stiff headwind, net uphill. Then I rode 1000+ back to Dull-Aware using strictly mid-grade, net downhill, same road, no wind. The regular gave me about a mile and a half more per gallon, no pings, no problems. Then two weeks later we rode 700 miles to New York and back via circuitous routes using premium. I got 4 mpg less on premium. All about the same time of year, same load, freeway speed (I usually set the digital cruise control at 85 indicated). This year, kept records down to Appalachia via numerous twisty roads, across to Gatlinburg, the Dragon, the entire length of the BRP and Skyline, and home. 2,000 miles all told. Twisties, freeway, everything but commute traffic. Averaged about 50mpg. That's 55 on country roads; 45 on freeways.

But the R1200CLC has 1:10 compression; the R1100R likewise; whereas the R12R I believe squeezes tighter than either.

My R1100R the previous owner always ran on premium. She rattles a mite at low RPMs full throttle regardless what I put in. Have to get in the habit of keeping her revs up, compared to the CLC. I will reset the motronic next fill-up, put in regular, and see if she can learn to like it.

[Enjoy-Rider]

I read thru this whole thread and was astonished that no one yet pointed out that......

We have all been waiting for yóu to tell us, at least I didn't know that US octanes are not the same as European octanes!! Pffff, anóther difference, apart from the miles, gallons feet, inches etcetera
But I have been wondering indeed that in the US you have octanes in the eighties

So more octane is less power.
The right grade for the engine is the deal.

But less octane can also be less power. Because then the detonation sensor retards the ignition (don't shoot me if I explain this wrong, I'm not a professional and besides it's difficult for me to explain in Englisch which is not my native language).

So what's your conclusion? You've mentioned correctly that the R12R has a higher compression than the R11R. BMW tells us to use premium (98 octane in Europe). So this should be the right grade. But I have also used regular (95) now and than, and I didn't see any difference in power (although I'm not a driver that rides on the edge if you know what I mean) and in usage.
But does that mean you can álways use regular? The dealer says you can use regular as long as you use premium every three or four times that you fill up your tank again .
So what's wisdom?

[cheelleebutt]

Most of the big name gas manufacturers (e.g. Chevron, Shell, Mobil, 76) put a cleaning agent into their premium gas. Most likely this is the reason for the dealer mentioning a tank full of premium once in a while. I haven't put anything other than premium in my 12r, but I did try mid grade a couple of times when I had the 12gs. I noticed the difference in acceleration. No, no Dyno charts, no technical knowledge of how gasoline is made, but I can just feel the less enthusiasm in the bike when I try to gun it.

My way of thinking, if the premium has cleaning additives that keeps the internals just that little bit cleaner and give me a little more of a kick during acceleration, I'll stick to it. Has anybody tried race fuel? 104 octane or something like that.

[thepeacebullgrunt]

Hi !

I don't know if I am getting paranoid or what but I feel my bike slightly less performant when anywhere in Los Angeles I am filling up my gas tank with 91 Mobil instead of the 91 of my local 76 Station. I feel the bike less torquy, punchy..little less power... no big deal so far ! but I just notice a little difference which kind of annoy me. I wonder if the Los Angeles vincinity riders noticed something ? as I have heard on this forum I think about issues with gas quality in California...

Hope the week end was great
for all of you guys & girls !

PS: I am digging up this old thread
just because I don't want to annoy the crowd
with an eventual recurent question.