~Since 2004~
A site about memories, thoughts, photos, and unrepentant opinions about motorcycles and motorcycling after four decades of twisting the throttle.

Saturday, April 12, 2008

Your Mileage May Vary

I know to our fellow riders in other countries American fuel seems cheap but we're stuck here in a vast land and getting much of anywhere beyond the city limits and back often takes multiple tanks of gas. Where I live the interesting, curvy roads don't even start until the first tank of gas is half gone and that's with a 6 gallon tank.

With the price of gasoline heading every higher some motorcycle guys are talking about running lower octane gasoline AKA "regular" in their bikes even if the manufacturer calls for higher octane premium fuel. If you're not sure exactly what octane means you can visit Wikipedia for a better explanation than I can give you without you nodding off or getting bored and leaving early to visit your favorite bikini biker babe site. (Shame on you, what would your momma think?)

My Aprilia Caponord owners manual recommends premium fuel for the bike and I always put premium in the tank. My Gold Wing uses regular (87 octane) but I usually put premium in it. Why? I had a long conversation recently with a vehicle test engineer and he told me that all the major brand premium fuels contain extra additives that are helpful in keeping a fuel system cleaner than regular gas will. Fuel will begin to leave microscopic deposits on some parts after as little as a week of sitting idle. Good quality fuel will largely clean this away. He was quick to point out there there was no performance advantage under normal conditions in running premium over regular unless the engine required the higher octane. Regular fuel does contain some cleaners but not in the same degree that premium does.

I also had a discussion with the head chemist at a major refinery that supplies test fuel to several car companies and the EPA (I used to do all the fuel purchasing at work) and I asked him the key question: "Is one brand of fuel really better than another?" The answer: "Yes. And I hate to say it but Chevron's Techron is just as good as they claim it is." And he worked for a Chevron competitor.

Some other tidbits about fuel I've learned over the years at work and from people in the fuel biz: Production fuel from major suppliers is amazingly consistent but variables out in the real world can include black market gas from who knows where, stations who will put regular in a premium tank, stale fuel if a station is a low volume station, and of course just plan crap in the storage tanks because keeping them clean and changing line filters costs money. Fuel left in the sun in a translucent container (plastic ones like racers love) will begin to lose volatility in as little as three hours. In a street bike that probably means zilch, when diving into the last turn of a race and trying to make a pass for first it might mean more.

So, your beloved bike might run fine on lower octane fuel but for improvement in the long term function of the fuel system, brand name premium is the better choice. Even if your bike is designed to run on regular, a tank full of quality premium now and again will make it smile and like you better. I have to think too, that those wily Italians would not recommend premium for my Aprilia if it wasn't really necessary as they'd rather spend money on good wine and women.


Doug C said...

"... but Chevron's Techron is just as good as they claim it is."

I always suspected thhis to be the case but everyone kept telling me differently.

Interesting post!

Crusty said...

Great advise Doug...I have seen the efffects of poor fuel choices from the inside of a carburetor. Especially with the 10% alcohol these days. -Crusty

Ronman said...

Great posts as always. Thanks for the wonderful information. I find that I even put premium fuel in my lawnmower. Overkill? Probably.


FLHX_Dave said...

Glad I only use Chevron. You got me with the bikini link. I have a Harley but I always get a laugh out of your bits on that subject. Thanks for the Wikipedia info. I have heard that I should use lower octane at higher altitudes. Looking at that info I guess it wasn't crap? Thanks for the post.

FLHX_Dave said...

Oh yeah, I really like that snap you took of the pump. Great shot.

Anonymous said...

good topic, Doug. Thanks for the informative post!

Unknown said...

Well done too bad we have to make a choice between fuel or women!

Desert MotoRat said...

Timely post about fuel. I've got a habit of only filling up at stations that have separate hoses for each grade of fuel. It seems to me that on the pumps with one shared hose you probably get a gallon or so of the last fuel pumped(usually 87 octane). Seeing that I ride a sportster with a 3.3 gallon tank it makes a difference. I don't know the mechanics of fuel pumps, but it seems logical. I guess I'll look for Chevron stations in the future.

Desert MotoRat said...
This comment has been removed by the author.
Mr. Motorcycle said...

Long time ago, before I knew any better, I was using 87 octane in my bike, till my mechanic scolded me after cleaning our my carb.
He also said something about getting pre-ignition problems prior to switching to higher octane.

Good post.

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