shelf life: premium vs reg?

[flyerdan]

There is a supplier here in Salem that hawks their ethanol free gas for small engines on the radio, and there is a site that lists stations that sell it across the country. Pure-Gas.org Probably worth the added cost for over wintering and keeping some chainsaw gas on hand.

I've heard that gasoline travels through pipelines to distribution centers, so it pretty much all comes from the same horse and brand specific additives are added on site. Also heard that the midgrade is created at the pump by blending regular and premium, which would make sense.

 

[3v0]

I switched to non alcoholic premium for the small engines this summer. One of the 2 cycles requires the octane and my riding mower is so carboned and runs better on the high test. (yeah my bad) It was a lot easier to feed them all the higher octane. But now you guys have me wondering if that is a mistake!

When I parked my 72 C-50 truck 8 years ago I put stabil in the tank and ran it to get treated gas into the carb. This fall I drained the tank and put in newer gas. I then removed the line from the carb and cranked it to flush the old gas out of the lines. It took a bit of fiddling but I got it running and it sounds good.

I figured the carb would need rebuilding and glad to be wrong. Maybe it was the stabil or maybe just lucky with the gas. It is also worth mentioning that newer gas was pulled out of a non running car purchased recently. Thinking that gas is 6 months old. It smelled good and I treated it with seafaom after the engine started.

I am starting to think there is little rhyme or reason to this.

 

[big bubba]

My opinion are these.

Octane may not help prolong shelf life but a better additive package that comes with a premium grade gas may.



EDIT: To check my thinking I consulted wikipedia which lists 5 possible additive package compents that stabilize gas. I wonder if it if they publish the additive package contents.

Antioxidants, stabilizers
Butylated hydroxytoluene (BHT)
2,4-Dimethyl-6-tert-butylphenol
2,6-Di-tert-butylphenol (2,6-DTBP)
p-Phenylenediamine
Ethylene diamine

that's kinda what i was wondering when posting the question thx

 

[jodebg]

I use 87 octane and add a small amount of both Marvel mystery oil and Redline fuel system cleaner to the storage can before filling with gas. Never had a problem starting or running my machines, even after the gas sat in machine all winter. Also add the same 2 additives to my 2 cycle chain saw gas can...starts right up and runs strong.

 

[Jkott]

Wow. There is way too much "friend of a friend" and "I heard once..." In this thread and not nearly enough fact.

Octane is resistance to ignition. Higher the number, the less flammable it is. You want the lowest octane your engine runs well on. It is what your engine computer is tuned for and will give you the best performance and economy. Putting in a higher octane (notice I didn't say grade) than your engine needs means you aren't getting the performance your engine was designed for. The only engines that NEED high octane are high compression engines which need a less flammable fuel to keep the compression heat from igniting the fuel before the spark does. Early ignition is "knocking" and is bad for the engine.

For fuel in lesser used engines, you want non-oxy fuels or the pure gas you are talking about. Ethanol is an alcohol, and any alcohol will attract water and it separates from the gas and breaks down faster. Even stabilized e-10 fuel ages in months. Stabilized Non-oxy fuels can be usable at a a year, but won't be in top shape.

And yes, the gas itself in the tanker truck delivered to all stations is the same. The difference is the additive package. I feel sorry for the station getting fuels by a lazy driver delivering the wrong grade to the tanks. Certain engines need the correct fuel to run correctly and at the right performance level and not getting the advertised grade is bad. The state will catch up to those stations eventually.

Running 91 octane non-oxy in small engines (at least in Minnesota) is a compromise. 87 octane is much better for them, but our state really wants us using e-10 or higher. As a compromise to collector and hot rod owners, they allow stations to apply for a permit to sell 91 octane non-oxy fuels in pumps labeled that it's a crime to put it in a modern auto. 91 isn't optimal for all vehicles but it will work a lot better than 87 in an engine that *needs* 91. And it's a lot more expensive than the e-0 87 I would rather have" but hey, the state is here to tell me what's good for me, right?

 

[TomSeller]

Wow. There is way too much "friend of a friend" and "I heard once..." In this thread and not nearly enough fact.

Well stated. I use the octane my manuals recommend in each engine for the reasons you talk about. I also use non ethanol in all the small engines that might be subject to a few weeks without use.

 

[sld]

Ethanol gas loses octane rating as it absorbs water. The reason for storing 91 is that by the time you use it, it may only be 87.

 

[TomSeller]

Ethanol gas loses octane rating as it absorbs water. The reason for storing 91 is that by the time you use it, it may only be 87.

If you use non ethanol 89 octane in a vent free container does it lose octane?

 

[Gary Fowler]

As I stated before;our marine gas is 91 octane non-ethanol......stores very well.I also add marine stabil and Startron.My boat,mower,trimmers ect. sit idle for eight months with no problems.I fill the tanks and run for about five minutes.I believe the Stilh oil has Stabil added to it,my two cycles sit for long periods with no problems at all.

One station sells only pure gas in 3 grades and then has Marine gas. Just wondering what the marine gas has/doesn't have that is worth about $1 per gallon more. He already sells 87,89 and 91 grades plus diesel and now Marine Grade.

 

[murphy1244]

What is Marine Gas anyway?