Small boat owners are constantly faced with the dilemma of whether to drain the fuel mixture after the navigation is complete or leave it in the tank until the next season. two-strokewhere the greasing of rubbing vapors occurs directly by burning the oil added to the fuel.
The chemical composition of the modern benzo-oil mixture is unstable and susceptible to oxidation, which can lead to serious consequences for the carburetor and piston group. Understanding the degradation processes of the components of the mixture will allow you to avoid costly repairs and problems with starting the engine in the midst of fishing.
The shelf life of a finished fuel mixture is much shorter than that of pure gasoline, due to the interaction of additives and oils with oxygen. In this article, we will discuss in detail what factors affect fuel safety, how to properly preserve equipment and why old stocks of the mixture can cause expensive units to fail.
Process chemistry: why the mixture loses its properties
Gasoline, even of high quality, is a volatile liquid made up of many hydrocarbons that evaporate over time or react with oxygen. two-stroke The picture becomes more complicated: the organic components of the oil begin to oxidize faster, forming resinous deposits and lacquer plaque.
The main enemy of the mixture is a process called bundling, where the oil stops being evenly dissolved in gasoline and precipitates or forms a jelly-like mass, which is caused by temperature, humidity and time, making storing the mixture in transparent containers in light extremely undesirable.
⚠️ Attention: Using a stratified mixture, even after careful shaking, can cause pure gasoline to enter the cylinder without lubrication, causing an instant piston jack and engine jamming.
Modern synthetic oils have better stabilizing properties than mineral counterparts, but they also cannot indefinitely retain their specifications in a mixed form. fuel-tank and a carburetor.
Use only special canisters made of opaque plastic or metal labeled "Fuel" to store the mixture, as light accelerates the chemical degradation of the components.
Real storage time of benzo-oil mixture
The answer to how much gasoline and oil can be stored depends on many variables, but there are averaged technical standards set by engine manufacturers. For a standard mixture made from a quality AI-92 or AI-95 and synthetic oil, a safe period of 2 to 4 weeks is considered to be a period of storage in ideal conditions.
If the storage temperature rises or the container is not sealed, this period is reduced to a few days, and many boat owners mistakenly believe that the mixture can stand all winter, but the chemical processes do not stop even at low temperatures, although they slow down.
The following table shows the dependence of the useful life of the mixture on storage conditions and the type of components used:
| Type of oil | Storage conditions | Maximum time limit | Risk of stratification |
|---|---|---|---|
| Mineral | A dark, cool place. | 2 weeks | Highly |
| Semi-intelligent | A dark, cool place. | 1 month | Medium. |
| Synthetics (JASO FD) | Hermetically, without light. | 1.5 - 2 months | Low. |
| Any butter | In the sun, temperature changes | 3-5 days | critical |
It is worth noting that the presence of alcohols (ethanol) in gasoline, which is often found in modern fuels, drastically shortens the life of the mixture. Ethanol is hygroscopic and actively absorbs moisture from the air, which leads to phase separation and the formation of an aggressive water-alcohol fraction at the bottom of the tank.
Factors accelerating fuel deterioration
There are a number of external and internal factors that can turn a quality fuel mixture into an unusable substance in a matter of days. The first and foremost factor is contact with air: the more free space (air cushion) in the canister, the more intense oxidation occurs.
Temperature is also critical: Storing the mixture at temperatures above +20°C accelerates the polymerization of oils, and the freezing and thawing cycles (if the canister is in an unheated garage) contribute to the condensation of moisture inside the container.
- 🌡️ High ambient temperatures accelerate the evaporation of the lighter fractions of gasoline, making the mixture poorer and changing its octane number.
- 💧 The ingestion of water through a loose cover or condensate from the air leads to stratification and corrosion of the metal elements of the fuel system.
- ☀️ Direct sunlight initiates photochemical reactions that destroy the structure of additives and oils.
- 🧪 The presence of copper or brass parts in the storage tank (e.g., in old cranes or hoses) can catalyze fuel oxidation.
It's important to understand that even in sealed factory packaging, the oil has its shelf life, and in a mixed state, its properties degrade exponentially, so buying oil for the future after opening the package and mixing it with gasoline makes no sense.
Signs of an unsuitable fuel mixture
Before you can put the mixture in the tank of the outboard motor, you need to conduct a visual and organoleptic assessment of its condition, and ignoring the signs of fuel degradation can lead to the fact that you can not start the engine away from shore.
The first sign is a change in color: the fresh mixture usually has a bluish or greenish hue (depending on the dye in the oil), while the old mixture becomes dark, cloudy or brown, indicating the beginning of the oxidation process and the formation of resins.
⚠️ Note: If you notice jelly-like clots, sticky sediment or floating flakes at the bottom of the container, such a mixture is strictly forbidden to use in the engine without careful filtration and mixing with a large amount of fresh fuel, and it is better to dispose of it.
The smell is also an indicator: fresh fuel smells sharp and characteristic, while spoiled mixture can acquire the smell of varnish, sour chemistry or just weathered, dull aroma. If the mixture has lost its volatility and began to smell "heavier", this is a bad sign.
Can an old mixture be resuscitated?
Theoretically, if the mixture simply lost its volatility but did not dissect, it can be mixed with fresh gasoline in a ratio of 1:3 or 1:4 and used in unpretentious equipment (chainsaws, trimmers).
Rules for the conservation of the outboard motor for the winter
Proper preparation of the equipment for long-term storage is the key to its longevity. There are two main approaches to conservation, and the choice depends on how long the engine will stand idle without operation.
The first method involves a complete drain of the fuel mixture from the tank, fuel hoses and carburetor, which requires shutting off the fuel crane, disconnecting the hose from the engine and letting the fuel drain into the prepared container, then starting the engine and letting it produce the remaining fuel until it stops completely.
The second method, recommended by some manufacturers for very long storage, involves filling the system with stabilized fuel. fuel-stabilizerAfter that, the engine is given to work for 5-10 minutes to stabilized gasoline filled the carburetor.
☑️ Checklist for winter preparations
Regardless of the method chosen, you need to make sure that there is no aggressive environment left in the system that could damage the rubber seals or membranes of the carburetor during the winter.
Use of fuel stabilizers
Fuel stabilizers are chemical additives designed to slow down oxidation and prevent resins and varnish formation, and are especially effective if you plan to store the appliances with a full tank for several months.
The stabiliser works by binding free radicals and preventing the polymerization of hydrocarbons, but it's important to understand that the stabilizer can't restore the already spoiled fuel, it only slows down the spoilage of fresh.
When choosing a stabilizer, pay attention to compatibility with two-stroke engines and the presence of anti-corrosion additives. Add the drug strictly according to the instructions, usually at the rate of 10 ml per 1 liter of fuel, and be sure to mix the mixture.
The stabilizer extends the life of the mixture to 12 months, but only if it was made from fresh gasoline and stored in the right conditions.
Recycling of the old fuel mixture
The issue of disposal of spent or spoiled fuel is acute, as it is strictly forbidden by law to drain it into soil or reservoirs and is dangerous to the environment. One liter of gasoline can pollute thousands of liters of groundwater.
The easiest way to dispose of the mixture is to gradually burn the mixture in the engine, mixing it with a lot of fresh fuel, for example, you can add 100-200 grams of old mixture to a full tank of fresh fuel on each trip.
If the mixture has obvious signs of stratification or contains water, it is impossible to burn it in the engine, in which case it should be handed over to special oil reception points or use the services of specialized organizations for the disposal of chemical waste.
Frequently Asked Questions (FAQ)
Can I store the mixture in a plastic water bottle?
No, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no. No, no, no, no. No, no. No, no. No, no. No, no. No, no. No, no. No, no. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No.
What happens if you pour a mixture that has been standing for six months?
There's a high probability that the engine won't start or will be interrupted, and the worst case scenario is that the oil that has fallen into the sediment will not oil the cylinder, causing overheating and bullying, and the carburetor's jellyboxes may coking up and the fuel membranes may fail.
Should I add fresh oil to the old mixture before use?
No, it doesn't make sense. It's not the amount of oil that's involved, it's the change in the chemical structure and the loss of lubricating properties, and adding fresh oil to oxidized gasoline will not restore the properties of the mixture, but will only increase the amount of soda.
How to distinguish gasoline with oil from pure gasoline?
The mixture is usually colored (blue, green, red) due to the dye in the oil. Pure gasoline is transparent or slightly yellowish. It is also more oily to the touch, and when rubbed between the fingers leaves an oily trace that does not evaporate for a long time.