Mixed Fuel, When to Discard?

Curtis Bosarge · Joined: 18 Jul 2001 Posts: 28 Location: Des Allemands, La.

Is there a definitive answer to the question of when to dump your pre-mixed race fuel (or put it the weed-eater/go-ped)? How long does it last and what are the consequences of using it, power loss or engine damage?

Learning something new everyday.

Thanks,

Curtis

Erik Frank · Posted: Wed Oct 24, 2001 5:41 am Post subject: Mixed Fuel, When to Discard?

At every race: fresh fuel...always.

The Lawn-Boy makes a great waste fuel disposal unit! Runs quite happily on B-32 and Redline oil. I just transfer my leftover fuel from a race weekend over to the lawn and garden fuel can and I'm good to go.

You do have all two-stroke powered lawn and
garden equipment, don't you?

-erik

Jeff Mulvihill Jr · Posted: Wed Oct 24, 2001 6:46 am Post subject: Mixed Fuel, When to Discard?

quote:
Originally posted by Erik Frank:
At every race: fresh fuel...always.
-erik

Why?

Erik Frank · Posted: Wed Oct 24, 2001 8:12 am Post subject: Mixed Fuel, When to Discard?

Why?

Because every race for me means every road race, which is (at best) once a month. I want fresh fuel for tuning consistency, and performance. When you're tuning an engine at or near the combustion detonation limit, you don't want old fuel!

The shop I buy fuel from typically turns a drum around within a week, so I am reasonably assured that the supply is fresh, too.

Week to week....probably not a big deal, provided its stored tightly capped. Also depends on the type/brand of fuel!

-erik

Bob Chiras · Joined: 30 Jul 2001 Posts: 198

We did tech inspection on fuel last weekend at a local track.

A shifter driver had raced the prior weekend and used the same fuel which he stored in a 5 gallon container (plastic fuel jug).

The reading was 50 points higher on the meter and within 10 points of being illegal.

The driver was very surprised that one week of cool and dry weather and the fuel in a closed fuel jug could change the fuel reading so dramatically.

Be safe it is a low cost investment to get fresh fuel.

Unless you have a meter and a very controlled environment the best bet is to recycle the fuel after each race weekend.

Tim Doll · Posted: Wed Oct 24, 2001 6:33 pm Post subject: Mixed Fuel, When to Discard?

quote:
Originally posted by Bob Chiras:
A shifter driver had raced the prior weekend and used the same fuel which he stored in a 5 gallon container (plastic fuel jug).

The problem is not storing "mixed" fuel, the problem is improperly stored fuel. Store your fuel in a plastic jug and you are asking for trouble. Some of the components of racing gas will pass right through a plastic jug.

Contrary to popular belief, gas DOES NOT deteriorate when mixed with oil. If PROPERLY stored, mixed fuel will last indefinitely without significant deterioration. Proper storage means tightly sealed in a steel container. I have a digitron gauge (I often do fuel tech), and "fresh" and (properly stored) six month old fuel will read within a couple points on the meter.

The way I look at it, you have a choice: You can get a cheap plastic gas can and dump $5 dollar/gallon gas (plus whatever you spend on oil) into your lawnmower, or you can spend ~$15 on a quality steel gas can (so called "Jerry" cans work great) and use that expensive fuel in your race kart and put $1.50 gas into the lawnmower.

Tim

John Denman · Posted: Wed Oct 24, 2001 10:06 pm Post subject: Mixed Fuel, When to Discard?

quote:
Originally posted by Erik Frank:
At every race: fresh fuel...always.

You do have all two-stroke powered lawn and
garden equipment, don't you?
-erik

Works OK in a Briggs lawmower too, and the top end is well lubed.

Now if only my driver would cut the grass more often to use up the fuel.

Jeff Mulvihill Jr · Posted: Wed Oct 24, 2001 10:27 pm Post subject: Mixed Fuel, When to Discard?

Does fuel/oil have a shelf life? I just want to understand your rationale for getting new fuel every month/event and or NOT using the old fuel in your motor. What do you do with the unmixed, unused fuel? I'm not running 5 gallons in a weekend...

Bob, what kind of "meter" are you using to test the fuel? Going up 50 but still legal doesn't mean anything to me, I don't have a point of reference... is UP bad?

Jimmy Moore · Joined: 26 Jul 2001 Posts: 664

One thing you can do is to get a smaller gas tank. My tank only holds 1/2 gal. I use about 1/2 gal. for one race weekend but, I have to mix 3 qts. so that the tank will still feed right at the end of the feature. When the day is over, I only have an extra qt. to deal with. Some use a big tank to make weight and they have to have 1 1/2 gal. in the tank at the scales.

Oil will start to break down as soon as it's mixed with gas. Would you use pre-mix from last season? Does it loose a significant amount of its lubrication properties in a week? WHO KNOWS. I do know that synthetic holds up better than castor if you believe what you read on the lables. I make up my pre-mix the morning of the race to get the best out of the lube, after that I cut it down to 32:1 and use it in my 2 stroke mower. The trick is to have a small tank and mix just what you need for that day.

Bob Chiras · Joined: 30 Jul 2001 Posts: 198

Digatron makes a fuel meter. There is a processto cleanthe probe and then to get aa baseline of the fuel.

The readings on the display of the instrument indicate a minus level for fuel which is determined to be within specification when the reading indicates a positive reading the fuel is considered out of specification.