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CSpackler
04-25-2010, 06:51 PM
Hi-
I apologize if this has already been answered elsewhere here. I actually emailed these questions to several major oil companies and they could not answer them, but these are questions about gas as it pertains to two stroke engines. Does gas degrade over time? If so, how much over what period of time? Does octane degrade over time? If so, how much over what period of time? Do fuel stabilizers work? How will degradation of fuel or octane effect two stroke and even four stroke engines?
Thanks

cgaengineer
04-26-2010, 06:24 AM
Fuel does degrade over time. How much? It depends on how well it is stored. If you keep the tank full it should last about 1 year without any trouble. The less air in the tank the better. I have had fuel in my generator for over a year and it still smells fresh and it still runs my machine.

I have never used a fuel stabilizer because I rarely leave a fuel tank full of fuel with the exception of my generator, but I do not use stabilizer in it either.

AI Inc
04-26-2010, 06:26 AM
I have reaD THAT IT WILL BREAKDOWN WITHIN 30 DAYS. I have had problems with it in both my bike and my boat.

cgaengineer
04-26-2010, 06:46 AM
I have reaD THAT IT WILL BREAKDOWN WITHIN 30 DAYS. I have had problems with it in both my bike and my boat.

I would say temperature and storing conditions play a large part in how long it lasts. Fluctuations in temperatures cause condensation which is why I suggest storing equipment with tank full to eliminate as much air as possible. Here in GA I have not had problems storing for over a year, but if I know it will be stored for a long time I will drain the float bowl prior to storing. This almost eliminates starting and carb problems at next use.

No doubt in my mind that it starts breaking down as soon as it leaves the refinery, but how much I have no idea.
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KarlP
04-26-2010, 10:39 AM
I have reaD THAT IT WILL BREAKDOWN WITHIN 30 DAYS. I have had problems with it in both my bike and my boat.

The problem is either gas evaporating in the carbs and leaving all the residue behind or ethanol in the "gas" attracting water. I never add stabilizer to my snowblower, lawnmower, motorcycle, generator, or outboard but I do turn off the petcock and run all the gas out of the carb at the end of the season. Never had a problem doing that.

As far as the ethanol goes, you can either get gas cans that seal really well and hope for the best OR donate a few $100M to your own lobbyists to fight the corn lobbyists are are sticking us with this horrible fuel.

cgaengineer
04-26-2010, 10:56 AM
The problem is either gas evaporating in the carbs and leaving all the residue behind or ethanol in the "gas" attracting water. I never add stabilizer to my snowblower, lawnmower, motorcycle, generator, or outboard but I do turn off the petcock and run all the gas out of the carb at the end of the season. Never had a problem doing that.


As far as the ethanol goes, you can either get gas cans that seal really well and hope for the best OR donate a few $100M to your own lobbyists to fight the corn lobbyists are are sticking us with this horrible fuel.

Or you could do what everyone else does and add Seafoam which contains more alcohol...what a great idea!

I have never had problem draining float bowls so I will continue doing that myself and not play into the fuel stabilizer and additive industry.
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betmr
04-26-2010, 11:37 PM
Gasoline turns to Varnish over time. This Varnish, gums up the small ports, screens and passages in the Carburetor, as well as helping to clog fuel filters. Today's small engines are not really compatible with Oxygenated (Ethanol) fuels. As well as attracting corrosion causing moisture out of the air, the Ethanol in today's Gasoline is suspected of having adverse effects on Gaskets, rubber, and plastic parts associated with small engines. Fuel Stabilizers, in my opinion, do prolong the longevity of fuel, but are not a cure all.

When I prep my equipment for long term storage, I drain all the fuel, and run them till they are empty. I put a small amount of stabilized fuel in, and run them empty, again. By doing this, any small amount of gas that remains, is treated. I then add a teaspoon of motor oil in the spark plug hole, turn it over a few times to distribute on the cylinder walls, set the piston at top dead center (A moot point in a twin), and put the plug back in.

As many Carburetor's as I've had to dismantle, clean and rebuild, I never leave a stored piece of equipment with fuel in it.

Nosmo
04-27-2010, 05:40 AM
I use Stabil in my gasoline for the mower during the period it is in storage. I have not had a problem with the gasoline going bad during the time the mower is sitting idle.

For my 2-cycle trimmers I use 40-1 mixture and late in the season I add a little bit of Stabil. For my Stihl chainsaws which use 50-1 I use Stihl 2-cycle oil which has a stabilizer added to it from the manufacturer.

Nosmo

cgaengineer
04-27-2010, 05:46 AM
I don't doubt the effects of alcohol in a fuel system. In my years growing up I raced karts that ran on 100 percent methanol, if you didn't run gasoline through them after racing and drain the oil and replace with fresh oil the steel gas tanks would rust and the aluminum parts would corrode. If stored without prepping the oil would turn all white and milky from the methanol. I am sure ethanol causes corrosion, but I suspect at only 10 percent that this is minimal but it still happens. If you insist on storing with fuel in the system your best bet is to store with a full tank. Stabilizers may help, I just don't use them. Around here we have about 2-3 months of really cold temps where a piece of equipment may sit, for me it easier to leave fuel in the equipment and just start them from time to time.
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CSpackler
04-27-2010, 06:45 AM
Here is what one oil company wrote in an email response to these questions:
(Company Name) gasolines are manufactured to meet ASTM D4814 Standard Specifications for Automotive Spark-Ignition Engine Fuel. We sell fuel for automotive use and for all other uses such as marine, lawn mower, blower, weed whacker, all two cycle, etc. we recommend you consult your owners manual. Thank you for writing.

cgaengineer
04-27-2010, 06:51 AM
Here is what one oil company wrote in an email response to these questions:
(Company Name) gasolines are manufactured to meet ASTM D4814 Standard Specifications for Automotive Spark-Ignition Engine Fuel. We sell fuel for automotive use and for all other uses such as marine, lawn mower, blower, weed whacker, all two cycle, etc. we recommend you consult your owners manual. Thank you for writing.

You would have gotten more info if you had not written them.
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betmr
04-27-2010, 03:11 PM
Just checked both Toro & Billy Goat manuals. Both say best to run engines dry, before storage, to avoid gum and deposits. Say Stabilizer is "acceptable" alternative. Not the best, but "acceptable".

CincyWolf
04-28-2010, 12:03 AM
I highly recommend stabilizer. Homeowners should put stabilizer in every can of gas when you fill it up because you never know how much you are going to use that blower, string trimmer, hedge trimmer, chain saw, edger or mowers late in the season or for some of that equipment even during the growing season. I've never had a problem with stabilized gas. The only time I ever have a problem is when I forgot to use it.

Of course, most repair shops don't want homeowners to know that because they get rich doing a preseason tuneup and carb cleaning that could be avoided with stabilized gas.

Using all gas or draining can be good but you can also dry out some seals and gaskets while doing so. That is why I fill up the tanks with a double dose of Stabil in my tanks. Less air space for oxidation and my cricial components are in gas vs. drying out. It is cheap insurance.

CSpackler
04-28-2010, 07:24 AM
Wow, lot of different of opinions here. I did buy the stabilizer and I only buy high octane gas. I just hope I'm not throwing my money away.

cgaengineer
04-28-2010, 07:28 AM
Wow, lot of different of opinions here. I did buy the stabilizer and I only buy high octane gas. I just hope I'm not throwing my money away.

You are if you are buying high octane fuel. Most equipment is designed to run on 87 unless its Stihl and then its 89.
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CSpackler
04-28-2010, 07:32 AM
Well, that goes back to someone telling me octane breaks down every 30 days. (Plus I do have some Stihl equipment).

cgaengineer
04-28-2010, 07:53 AM
I'm gonna call BS on the octane breaking down in 30 days. No doubt fuel starts to degrade as soon as it leaves refinery, but octane breaking down by itself is not the case.

If Stihl calls for 89 then running 93 would be a waste. The reason they suggest 89 is a performance and heat problem. Running higher octane fuel in any engine designed for lower octane fuel is a waste, your performance will actually be less. The need for high octane would be for higher compression engines or turbo/supercharged engines. Higher octane fuels require higher temps to combust properly and are used to prevent premature ignition (detonation).
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piste
04-28-2010, 03:02 PM
Great thread. My standard operating procedure is to keep four 5-gallon containers of fuel for purposes of emergency supply and to use up as needed in mower, walk behind edger, snow blower, etc. (Have a separate one gal for 2 stroke Stihl trimmer). I'd rotate to make sure that I never had gas that was older than a year...usually not older than 6 months or so. Given that was my plan...I used highest octane I could buy figuring that after a given period of time it's composition would be better than that of lower octane AND the fact that it would burn cleaner when used....AND for good measure added some Stabil as Cincy posted above....never knew exactly how long I'd have the gas. But recently I was informed that using high octane in small engines is a BAD idea...due to the fact that they burn hotter which could cause problems in small engines? Anyone have any knowledge or thoughts as to the truth of higher octane being bad for small engines????

As far as gas breaking down....EVERYTHING changes chemical composition over time due to various influences...it's just a matter of RATE of break down. However, my experience is that pretty much any gas stored with reasonable care and no additives will last at least a year if not more. I think there's a lot of hype on the notion of "bad gas" or "old gas". Yeah it happens but its often a scapegoat. I have seen more than once small engine repair shops not being able to diagnose a problem and copping out with the "old gas" ploy and cleaning the carbs. One place did that with my walk behind edger....gas was only a few months old. Took it home...still had problem...brought it back and...OH...guess what...bad fuel pump...problem fixed.

cgaengineer
04-28-2010, 03:42 PM
Higher octane fuel does not burn hotter. It differs from regular gas in that it has burn regulators added to it called octane. Octane serves no other purpose other than to ****** ignition. It does not provide more power except when used in an engine which has higher combustion temps due to less space between piston and head (volume), turbocharger or supercharger. Higher octane fuel is no cleaner than regular fuel, in fact it contains the same additives.
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cgaengineer
04-28-2010, 03:49 PM
It is a fact that premium fuel is actually older than regular fuel due to the fact that most people buy regular fuel when they fill up, so if you want the freshest fuel possible it will be the most popular fuel which is 87.
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cgaengineer
04-28-2010, 04:01 PM
http://science.howstuffworks.com/gasoline3.htm
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cgaengineer
04-28-2010, 04:04 PM
http://www.consumerenergycenter.org/transportation/consumer_tips/regular_vs_premium.html
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CSpackler
04-28-2010, 08:55 PM
I actually read both of those before posting. They do not address whether octane breaks down and it's effect on 2 stroke engines which operate quite differently than 4 strokes. Do 2 strokes also have electronic knock sensors. I actually do not think they do.

cgaengineer
04-28-2010, 09:54 PM
Regardless if it breaks down is moot as the fuel itself starts breaking down as soon as it leaves refinery and regardless if its 87 octane or 93 octane it would break down at the same rate...just because its 93 octane doesn't mean it breaks down at a slower rate.

2 strokes still compress a fuel mixture just like a 4 stroke and the process of taking in air and fuel and compressing it is the same, but rather than having conventional valves the valving is done either through a rotary valve or piston port with the exception of a Detroit Diesel which is a 2 stroke with conventional exhaust valves. Let's examine why 2 strokes lack knock sensors, for one they are usually used in smaller carb engines and usually run lower combustion chamber pressures (with the exception of diesel 2 strokes). My 4 mix engine takes the same oil/gas mixture as a 2 cycle yet its a 4 stroke...could it have a knock sensor, you bet, could a 2 stroke have a knock sensor...it most certainly could...nothing stopping any engine manufacturer from installing a knock sensor on any engine. Most small engines do not require them because the emission output is low enough and the combustion pressures are low enough that they are not needed...no sense of controlling every aspect of weed eater engines combustion and emission output if its not required by EPA.

So as different as you may think a 2 stroke is from a 4 stroke they both have an intake and an exhaust cycle, its just that the 2 stroke is doing 2 processes at the same time.
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cgaengineer
04-28-2010, 10:00 PM
And my supercharged Toyota Tacoma has a knock sensor but its not enough to stop detonation from the increase combustion temps due to higher pressures hence the requirement for 93 octane at all times or it will detonate in any gear at any speed. My Mazda MX6 Turbo car I used to own with 18 pounds of boost would detonate if 87 octane fuel was used even though it had a knock sensor. The MX6 would actually knock worse since it also had an intercooler. A knock sensors only function is to ****** timing when detonation is sensed, its not to correct the problems from the wrong fuel.
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CincyWolf
04-28-2010, 10:09 PM
cgaengineer has it right concerning octane. I believe octane ratings and what really matters is one of the most misunderstood things out there. The gas companies have convinced generations that premium gas is better vs. letting people know that it depends on a number of engine design and operating conditions. Most people think that high octane=high volatility=better performance and that is exactly wrong. High Octane=lower volatility because the octane ******s combustion so it doesn't ignite due to compression and heat before the spark is ready to light it up. You can make a lot of money betting people on this point and even when you show them how it works they still won't believe you.

The bottom line is to use enough octane for your engine to run without or with very minimal ping. Anything more for most engine applications is a waste of money. I've had many small high performance engines that needed higher octane fuel to maximize power. Car engines today have knock sensors and the computer will ****** timing if needed to eliminate knock. Therefore you can run lower octane fuel safely but you even if it calls for Premium fuel 92-93 octane but you'll take a performance and likely a fuel economy hit. However, ifyour car is designed and tuned for 87-89 octane you get no gain from using 93 octane except helping Exxon Mobil and your local gas station make more profit. Turbo or supercharged engines need higher octane and as mentioned above the onboard sensors are not enough to compensate for the more volatile fuel (lower octane).

RugerRedhawk
04-29-2010, 02:28 PM
Just use stabilizer in EVERYTHING that you're not going to use within 2 weeks time. The ethanol in all the gas isn't good.

cgaengineer
04-29-2010, 09:21 PM
Just use stabilizer in EVERYTHING that you're not going to use within 2 weeks time. The ethanol in all the gas isn't good.

Yeah, the octane really isn't the problem...its the hydroscopic nature of alcohol that will wreak havoc on fuel system parts...even 10%.
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CSpackler
04-29-2010, 10:09 PM
So it sounds like middle grade gas (as I have some Stihl stuff) and fuel stabilizer will do.

CincyWolf
04-29-2010, 11:57 PM
^ Yes. That about sums it up.

MDTRD
04-30-2010, 01:03 AM
And my supercharged Toyota Tacoma has a knock sensor but its not enough to stop detonation from the increase combustion temps due to higher pressures hence the requirement for 93 octane at all times or it will detonate in any gear at any speed. My Mazda MX6 Turbo car I used to own with 18 pounds of boost would detonate if 87 octane fuel was used even though it had a knock sensor. The MX6 would actually knock worse since it also had an intercooler. A knock sensors only function is to ****** timing when detonation is sensed, its not to correct the problems from the wrong fuel.
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Next time you're in Md, give Gadget a call. He can tune your Taco if you have his URD kit. I had a 00 Taco sc'd w/URD, 228hp/251tq to the wheels, Gadget tuned.

cgaengineer
04-30-2010, 05:40 AM
Next time you're in Md, give Gadget a call. He can tune your Taco if you have his URD kit. I had a 00 Taco sc'd w/URD, 228hp/251tq to the wheels, Gadget tuned.

I have read about his kit, the 2.7L could use it...it has a terrible flat spot when you accelerate...I doubt I'll ever be in MD so ordering his kit will have to suffice!

Toyota TRD....the R&D part of TRD should had done more testing before they released the kit.
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MDTRD
04-30-2010, 10:55 PM
TRD was full of themselves when the released their SCs. They did swipe his T-connection for boost and didn't give him credit. It's in their install instructions. Oh well. If you handy with computers, you can tune it yourself. Get a O2 sensor bung welded onto the downpipe and hook up a wideband O2 sensor for tuning.

cgaengineer
04-30-2010, 11:24 PM
I am pretty sure my problem is fuel related...as in not enough.
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cgaengineer
04-30-2010, 11:28 PM
My truck runs almost like its stuck in open loop.
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MDTRD
05-02-2010, 01:01 AM
Try a wideband o2 sensor to see where you fuel ratio is.