Fuel Grade Question

[Hardware]

I've done a search and didn't find anything here (admittedly a fairly quick one).  I've also done a Google search trying to figure this out...

Anyway, my owner's manual calls for either 98 ROZ/RON grade fuel for performance or 91 ROZ/RON for consumption.  

Are these ROZ/RON amounts the same as octane ratings, (i.e. does 91 ROZ/RON mean 91 octane)??

What octane grade does everyone else here run in their RT's?

[MadAmos]

this should give you what you need read the Measurement methods section
http://en.wikipedia.org/wiki/Octane_rating


Amos

[denydog]

   If I'm reading that link correctly, my bike may be a little malnourished.  

[motoguy128]

The biek seems a little smooth and friskier when I'm able to find 93 (AKI) gas on the road, but even 89, 90 or 91 seems fine.  I usually put in the highest available.  It's a $19k bike, why put cheaper gas in it, if it can get more power with higher octane.  You're looking at a $300 difference over 50k miles, or for me, about $50/year.  

The RT has a huge tank, so you can normally plan your stops near larger towns and find a Shell, Mobil or BP which will have a higher octane 93 or better premium available.

Everyone makes such a huge deal of gas prices rising.  a $0.40 rise in gas price, results in an increased cost of $200/year if you average 25mpg, and drive 12k miles per year.  BFD.

[et]

...
Everyone makes such a huge deal of gas prices rising.  a $0.40 rise in gas price, results in an increased cost of $200/year if you average 25mpg, and drive 12k miles per year.  BFD.

I agree with you in some ways but not others.

1) All those people driving humungous SUV's; or any other vehicle with more than three wheels; who only bought them to show-off their "wealth"; but can't actually afford them. Then they should just shut the heck-up about how much it hurts their wallets.
2) But for the rest of us who use our motorcycles as our main transportation; and not just joy-riding. The gas prices hurt us.
Until this past Sept; my commute was 80 miles each way. A tank of gas every day; almost $15.00 everyday !
(more than double if I had to use my compact pickup instead of my motorcycle)
In 2000 it was only costing me $5.00 a day for gas; for same commute.
So in seven years my gas cost tripled; but may paycheck didn't triple.

When the price of gas is rising faster than inflation; then we have a right to bitch about it.

As for Hardware's original question:
After reading MadAmo's link and this one: http://www.i-bmw.com/archive/index.php/t-7872.html; I would use premium grade fuel.

[bikerfish1100]

Your R12RT has anti-knock sensors, along with timing adjustment doohickeys, that will automatically detect a problem with low grade fuel and correct for it by adjusting the timing, before any damage can be done to the motor. That means you can run just about anything more potent than diesel and the bike will be happy. However, if you want the best performance out of her, give it the highest octane you can find. BUT, there's absolutely no need to fret about putting in low grade crap- the bike will be fine, just its acceleration will be not as strong.

[Lawn Dart]

I run 87 octane in my R12GS with no problems.  I ran 87 octane in ALL my bikes.

Higher octane:  if you car/bike is not a high compression motor (12:1 or so) then higher octane will NOT do you any good and WILL actually be slightly WORSE for your motor.

General rule of thumb:  use the lowest octane fuel available that does not cause knocking or pinging.

Higher octane does NOT equate to higher horsepower on it's own.  The motor itself must be able to compress the fuel more in order to gain the advantages of the higher octane rating.

To put it another way:  if you are an 800# overweight slob, eating a PowerBar isn't exactly going to help you!

[bikerfish1100]

Direct quote from BMW's website:

Type Air-cooled/oil-cooled Boxer twin-cylinder
Bore x Stroke 101.0 mm x 73.0 mm
Displacement 1170 cc
Horsepower 110 bhp @ 7500 rpm
Torque 85 lb/ft @ 6000 rpm
Compression Ratio 12.0 :1
Valve Gear HC, chain-driven
Valves 2.0 x 36.0 mm intake / 2.0 x 31.0 mm exhaust
Valves / Cylinder Four
Engine Oil Capacity 4.2 quarts
Engine Management BMW Engine Controller - BMS K
Fuel Requirement Premium Unleaded
Fuel Tank HDPE, internal pump and internal filter
Fuel Capacity 7.1 U.S. gallons including 1 gallon reserve
Charging System 720 Watts @ 14 Volts
Battery 12 Volts 19 Amps/hour low maintenance
Cooling System Air and thermostatically controlled oil cooling

The bike will be happier with the good stuff, but will run on whatever garbage you can find.

[tomek]

Higher C/R,higher octane requirement for given motor -agreed.But there is no fixed relation between CR and octanes all across the board.It all depends,bore size,combustion chamber efficiency,water or air cooling,camshaft duration,etc.
Try to run 12:1 on Big twin HD or old Triumph twin,they won`t ,without special brew.Same with old big V8.

On the other hand you can run 13:1 or better CR on SS 600 and motor will run perfectly on regular gas.

Many engines won`t ping on lower ectane gas but performance and fuel efficiency is reduced,but I do agree if motor is unable to take advantage of higher octane gas regular is better choice.

[goodhawk]

I read someplace in a BMW review, or maybe even BMW brochure, that 93 octane U.S. is even a little less than Euro premium, common 91 octane drops just  2 -4  H.P., more noticaable drop with 89 . . . thou as mentioned modern computer controls adjust the timing, etc so it's OK

[jsanford]

I run 87 octane in my R12GS with no problems.  I ran 87 octane in ALL my bikes.

Higher octane:  if you car/bike is not a high compression motor (12:1 or so) then higher octane will NOT do you any good and WILL actually be slightly WORSE for your motor.

General rule of thumb:  use the lowest octane fuel available that does not cause knocking or pinging.

+1.  My F650 doesn't like anything other than Unleaded regular, and I put mid-grade in the F800ST.

What I am choosy about is the brand of gas; I try only to feed the bikes Chevron.

[cbsnbiker]

My generic recommendation: use gasoline with the minimum octane recommended by the owner's manual.

For vehicles with anti-knock sensors: you can use lower octane, but with possibly lower power and/or gas mileage.

For vehicles without anti-knock sensors: using sub-minimum octane gas can cause knocking, which in turn can damage your engine.

In most instances, using higher octane gas than recommended won't hurt anything, but is a waste of money.