Two Cycle Fuel       

By Tim Ard

Forest Applications Training, Inc.


I have been involved with two-cycle tools since 1974, repairing, running, testing and teaching people about and how to use them. Fuel issues have been a major concern of two-cycle equipment manufacturers as long as I can remember. Old gasoline, improper mixing and carburetor adjusting have cost manufacturers, equipment owners and operators a lot of money.


On a trip to Sweden and Finland back about twenty years ago I was impressed by an idea that was readily available at power equipment dealers. The concept was a pure gasoline pre-mixed with two-cycle oil and packaged by the liter. The fuel was focused at the emissions value to the operator and the reduced damage to the engine and rubber parts.


A concern in many countries is the inhalation of two-cycle fumes and its long term effects on the operator and environment. This has become evident in the USA over the past decade.  The issue I am told stems from the additives in gasoline, the age of the gasoline, along with the mix oil and the engine efficiency.


As gasoline ages it loses its octane rating and becomes less volatile. When this happens it burns erratically and engine damage causing carbons and detonation occur. The oxygenators and cleaning agents used in automotive fuels can react negatively to the efficiency of two-cycle mixed fuel. Remember the auto fuel industry doesn’t spend a lot of time making gasoline work for the two-cycle equipment user. Pure gasoline, much like that used in the aviation industry, is more suited for the two-stroke fuel mix process.


Think about the detergents discussed in the auto gasoline advertising. They promote detergents to clean the inside of the car engine, reducing sludge and valve deposits that can be detrimental to your car’s engine. It’s good to be scrubbing the inside of your car engine so to speak with these agents. However, detergents are designed to separate oil and grease from the surfaces of your engine block and valves. Detergent basically lifts and separates the oil film from the metal and carries it off with the flowing oil and exhaust.  Now consider detergents, if they are doing their job, what is the effect on oil that is mixed with the gas to form your mixed two-cycle fuel. The minute you pour in the oil and shake it up in your gasoline container an amazing scrubbing bubbles operation begins to take place. The detergents in the gasoline are now fighting with the oil you added to separate them. They are just doing their job. The problem is you need the oil to stay connected with the gas to do your job with the two-cycle engine you have spent your savings on.


Alcohol containing fuels add another facet to the situation…  Let’s say you have your two-cycle machine adjusted and it’s running good. The fuel you had in the tank had little or no ethanol or methanol (alcohol) in it and it is running good. Now, you run out of fuel and go buy fresh gas and mix up a fresh supply in your can. It contains alcohol now because the new gasoline found at most pumps has 10%, or greater in some cases (I’ve heard rumor it may be even going higher, say 15%). Your engine rpm now runs higher and it idles differently, but you can get by… What’s really taking place? If you don’t re-adjust your carburetor you may be creating a lasting problem inside your now rapidly wearing engine.


You see, what I have been told, is that alcohol molecules take a larger hole to go through than  gasoline molecules. I don’t drink alcohol, but those that do, say that it is the reason they drink from a glass because it’s hard to drink fast and get enough from a small bottle opening. Just kidding! But it does make sense doesn’t it- given the richer adjustment needed for alcohol content fuel flow.


Now back to the carburetor of your two-stroke.  Your carburetor mixture screw setting is open let’s say two turns. There is a given amount of fuel that is passing by the adjusting screw. You add alcohol fuel to the situation and want it to pass by that same opening that was set for the pure gasoline. It can’t pass through at the same volume. The engine gets less fuel at the given setting. The important thing… a two-cycle gets its lubrication from where? The oil mixed with the gasoline. If you limit the fuel flow, you limit the lubrication needed inside your engine. If you adjust the screw open more you will remain lubricated but if you don’t…. eventual downtime. Potentially, the more fuel alcohol percentage in the gasoline, the greater the problem.  You can adjust to the situation but someone has to recognize the situation and do it.  The adjustment has to happen.


Consider the ethanol added to the gasoline is also sometimes a great solvent. It affects fuel lines, seals and other rubber parts too. It softens them and can cause all kinds of problems. You may have seen fuel lines in your saw or trimmer that has somehow turned to chewing gum consistency. Ethanol also collects water very well. This can help remove moisture from gasoline - but if it holds moisture in the two-cycle engine it can cause corrosion of aluminum and magnesium components.


I discuss carburetor adjustment in most all of my training sessions. Sometimes I am cautioned by the organizers or supervisors at the training sessions about doing so. They really don’t want their operators adjusting. They say, “I don’t want them to have a screwdriver nor use it.” I agree with that totally. However, I bet I hear of as many two-cycles damaged by lack of adjustment as I do adjustment. Actually more! If you fail to correctly adjust an engine that is not running properly, you stand a chance of engine damage.  An operator needs to know when a piece of equipment is out of adjustment. This is important to the life of the engine and operator safety.


Some people add a little extra oil to compensate for adjustment- adds a little extra lubrication - so they think. Oil holds heat and if not burned cleanly increases harmful emissions and carbon buildup. This unburned buildup and carbon inside the engine causes bearings to skate, piston rings to stick and scoring of pistons and cylinders.


Back now to my experience from the Scandinavian trip. The past few weeks I have been trying pre-mixed fuel from TruSouth Oil. I think it offers a long time needed solution to several two-stroke problems and efficiencies.


A typical example scenario…

While out in California on a recent training expedition I had a Husqvarna chain saw. I was using the saw fuel from the county park service supply. I asked how old the fuel was in their supply. They didn’t know the mix date. I asked if they have had any fuel problems show up, they replied not that they knew of. I then asked if they had any saws with cylinder replacements in the past few months. They replied two in the past year. Conversations turned to the fact they have problems with seasonal help and mixing fuel properly.  A common cause many experience.


I had to adjust the saw when I first started work and everything luckily ran OK with their fuel. You just don’t know however the lubrication you are getting until some time passes. I ran the mix for three tanks with no problems.


I started the third class out with 50Fuel. I had to re-adjust the idle and high speed settings a little leaner. That told me that the fuel from the county possibly had some alcohol in the mix, not so much that it couldn’t be adjusted out but the other negatives were still in place.  Adjustments have to be made if fuel isn’t consistent, elevation changes and as wear occurs in the engine.


The greatest thing is the 50Fuel ran great for the rest of the week and I know what it has in it. A very reassuring thought!


TruSouth Oil’s 50Fuel is going to answer many questionable two-cycle equipment issues. Some of the cost effectiveness of the purchase price will be realized in less repair costs over time, stabilized running efficiency and the following:


         No mixing mistakes

         No ethanol concerns

         No gas cans – Quart bottle convenience - Less waste

         Two year shelf life once opened and up to five year case life

         No fuel related issues with plastics and rubber parts

         Consistent carb adjustments and tank vapor pressure

         Less emission fumes

         Less can and supply storage space



Give 50Fuel a try and you weigh out the cost advantages. Check out their website or visit our eStore to get your supply.


If you have any questions or comments contact Tim Ard at .