The question of choosing the right fuel and lubricants for the outboard motor is a challenge for every owner of water equipment, whether an experienced boat owner or a beginner who has just bought his first boat. fuel-mix Or engine oil can be very expensive, even to overhaul the piston group or replace the entire power unit. Modern engines require attention to the quality of consumables, because engineers put high operating speeds and temperature conditions in them.
In this article, we will discuss in detail what the requirements of two-stroke and four-stroke engines differ, what the octane number of gasoline is optimal and why oil savings are a direct route to expensive repairs. Understanding the physicochemical processes that occur inside carburetor Or injector, will help you avoid common mistakes and extend the life of the equipment for many years.
Before you start filling the tank, you need to clearly define the type of your engine, because their approaches to lubrication and fuel preparation differ dramatically. exploitation Early use often leads to irreversible consequences that cannot be eliminated by simply replacing candles or cleaning the system.
Critical differences between two-stroke and four-stroke engines
The main design feature of the two-stroke engine is that the lubrication process of the crank mechanism and the cylinder-piston group occurs directly during the combustion of the fuel-oil mixture. oil It has to be added to gasoline in a specific proportion, and when it burns with the fuel, it forms a protective film on the rubbing parts, and then it is released out through the exhaust system.
Four-stroke engines are different: they have a full-fledged lubrication system, similar to the car, where oil circulates in a closed loop, washing parts and not burning in the combustion chamber (in ideal conditions). pure-gasolineAnd the oil is in a separate crankcase, and it requires periodic replacement, but not mixing with fuel, and trying to add oil to gasoline for a four-stroke engine will cause candles to coking, soaking, and failure of the catalyst.
It's important to understand that these types of engine oils have different chemical bases and labels: Two-stroke oils must have a high combustion temperature and the ability to completely burn without leaving solid deposits. Four-stroke oils are focused on long-term protection against oxidation and corrosion at high temperatures, but they are not designed to be burned.
⚠️ Attention: Never use car oil in two-stroke outboard motors. It does not burn completely, which leads to rapid formation of soot on the piston, sticking piston rings and overheating of the engine, which can cause jamming at the most inopportune moment on the water.
Modern two-stroke engines are often equipped with separate lubrication systems, where the oil is fed by a pump from a separate tank, but the principle remains the same - the lubrication occurs through the mixture. oil-pumpBecause its failure is equivalent to the operation of the engine without lubrication.
Requirements for gasoline: octane number and quality
Choosing the right fuel is the foundation of your motor’s long life. Most outboard manufacturers recommend using unleaded gasoline with an octane rating of at least 92 (research method) or 87 (motor method), and using fuel with a lower octane number can cause detonation, a spontaneous ignition of the mixture that creates a shock wave that destroys pistons and rods.
However, there is a nuance associated with the ethanol content of modern gasoline: many motor manufacturers limit the ethanol content of fuel to 10% (E10 marking). fuel-systemIt causes them to swell and break down.
Ethanol is also hygroscopic, which is the ability to absorb moisture from the air, and in water-storage or humid climates, this leads to the separation of the fuel mixture and the formation of a water-alcohol fraction at the bottom of the tank, which, when it enters the engine, causes corrosion and interruptions.
⚠️ Attention: Avoid fueling with an octane number above 95 (AI-95/98) unless explicitly recommended by the manufacturer. High octane number is often achieved by additives that may not burn completely in the outboard motor designed for the AI-92, which leads to the formation of deposits on candles and valves.
To ensure the stable operation of the engine, it is important to use fresh fuel. Gasoline that has been in the tank for more than 3-6 months, oxidizes and loses its properties, forming resinous deposits. If you plan to store the boat for a long time, be sure to use it. fuel-stabilizer Or completely remove the remaining gasoline from the system.
How to check the quality of gasoline by eye?
Good gasoline should be transparent, light yellow, without sediment, turbidity or rainbow film on the surface, and you can check the presence of water by adding some permanganate crystals to a transparent tank of gasoline — if they dissolve and paint the bottom layer pink, then there is water in the fuel.
Mixing proportions for two-stroke motors
Observing the right mixing ratios of gasoline and oil is the most important skill of the owner of two-stroke equipment. The wrong ratio of components can lead to two extremes: either the engine will get insufficient lubrication and jam, or will work with interruptions due to excess oil and the formation of soak.manuale) a specific motor, but there are common standards.
For most modern two-stroke engines up to 50-60 hp, the standard is 1:50 (2% oil) ratio, which means that 20 ml of oil must be added to 1 liter of gasoline. Older models or higher-powered engines (often Chinese-made or older Japanese series) may require a richer mixture of 1:33 (3%) or even 1:25 (4%).
During the break-in period of a new engine, the oil proportion often increases. For example, a manufacturer may recommend a mixture of 1:40 or 1:33 for the first 10 hours of operation to ensure increased lubrication when grinding parts. After the break-in period, the oil concentration is returned to standard.
For accurate dosing, it is convenient to use measuring tanks with a applied scale or special dispensing syringes. You should not rely on an eye meter or bottle caps, since an error of 10-20 ml per liter can significantly change the properties of the mixture. Always pour some gasoline into the canister first, then add oil, shake, and only after that add the rest of the gasoline for the final stirring.
The following is a table with the calculation of the amount of oil for different volumes of gasoline at a standard ratio of 1:50:
| Volume of petrol (litres) | Required volume of oil (ml) | Proportion | Percentage of butter |
|---|---|---|---|
| 5 litres | 100ml | 1:50 | 2% |
| 10 litres | 200 ml | 1:50 | 2% |
| 15 litres | 300 ml | 1:50 | 2% |
| 20 litres | 400ml | 1:50 | 2% |
| 25 litres | 500 ml | 1:50 | 2% |
Self-cooked mixture with high-quality synthetic oil and stabilizer can be stored for up to 6 months in a sealed metal canister.
Choosing engine oil: classification and standards
The market for oils for water technology offers a wide range of products, and an international classification will help to understand them. API TC The American Petroleum Institute, which guarantees high detergent and lubricating properties, also uses the Japanese standard. JASOFB, FC and FD classes are the most relevant for water engineering. FD class oils are the most modern, they provide minimal smoke and the best protection against high-temperature deposits.
Four-stroke engines are labeled FC-W (Four Cycle Water-cooled) oils, which are designed specifically for sea and freshwater applications, with enhanced anti-corrosion properties and the ability to resist emulsification (mixing with water).
Particular attention should be paid to the base of the oil: mineral, semi-synthetic and synthetic. Mineral oils are cheaper, but form more soda and require more frequent replacement or richer mixtures.Full Synthetic) provide better protection at high loads, are more easily mixed with petrol and burn almost without residue, which is especially important for engines with catalysts.
When switching from mineral oil to synthetic in a two-stroke engine, it is desirable to fully develop the old fuel mixture or thoroughly rinse the carburetor, since synthetics have a high detergent capacity and can raise old soda, clogging the jellywood.
When choosing oil, also consider the type of cooling of the engine. For water-cooled motors, standard TC-W3 oils are suitable. If you have an air-cooled motor (often found at very low power or specific models), it requires oil marked TC, since the temperature of the piston group is much higher there.
Refuelling procedure and safety measures
Proper refueling of an outboard motor is not just a mechanical action, but a process that requires compliance with safety and certain rules: the boat should be refueled only on shore, on a hard surface, away from open fire and sources of sparkling. Gasoline vapors are heavier than air and can accumulate in the hold or low points of the hull, creating an explosive concentration.
Use special fuel canisters with a nozzle-flame suppressor and a cut-off function that automatically stops the fuel supply when the tank is filled. Never fill the tank "to the end." Gasoline has the property of expanding when heated, and the absence of an air gap (compensatory volume) can lead to the fuel being squeezed through the tank. tank-lid or a pressure relief valve that could cause fire.
☑️ Safe refueling rules
After refueling, be sure to wipe the rags around the tank neck and the canister itself to prevent fuel from hitting the hot parts of the engine or into the water. If you use a remote fuel tank, make sure that the fuel hoses do not have cracks and the pump pear is mounted upwards (the shooter on the pear should look towards the engine).
⚠️ Attention: Smoking or using an open fire within 10 metres of a filling station is strictly prohibited, and static electricity can also cause ignition of vapours, so when filling from a large container, it is recommended to ground the canister, touching the metal part of the boat before opening the lid.
An important element of the system is a fuel filter-sludge, installed between the tank and the engine, regularly check it for water and dirt, the water in the fuel is the main enemy of the carburetor and fuel injectors, causing corrosion and engine stops on the go.
Features of operation during the break-in
The break-in period of a new outboard motor or engine after major repairs is critical to the formation of the resource, during which the rubbing surfaces of the piston group, bearings and gears are used, and a violation of the break-in mode can lead to local overheating and bullying, which will manifest after the end of the warranty period.
During the break-in, you must strictly follow the manufacturer's recommendations on operating time and load. Usually the process is divided into several stages: the first 10 minutes at idling, then work at low speeds, and only then a short-term increase in load is allowed. For two-stroke motors, it is often recommended to increase the proportion of oil in the mixture by 10-20% of the norm during this period.
Avoid long-term constant rotations (e.g. trolling at the same speed) during the first hours of operation, periodically changing the engine mode, allowing it to work at higher and lower rpms, which contributes to the uniform lapping of the rings throughout the surface of the cylinder.
Successful break-in lays the foundation for low fuel consumption, stable compression and no oil perspiration throughout the life of the engine.
After completing the first 10 hours of operation (or other interval specified in the instructions), you need to carry out maintenance: replace the oil in the gearbox (for four-strokes - and in the crankcase), check the tightening of the mounting bolts, clean the spark plugs from possible soak and replace the fuel filters.
Frequent errors and their consequences
One of the most common mistakes is to keep a boat full of gasoline without adding a stabilizer, and in winter, gasoline oxidizes, precipitates resinous substances that clog carburetor jets or injector nozzles, which require complete disassembly and ultrasonic processing, which is expensive and time-consuming.
Another mistake is ignoring the color of the exhaust. For a two-stroke engine, a light bluish haze is normal. If the smoke becomes black and thick, this indicates an over-enriched mixture (lots of oil or little air), which leads to loss of power and soot. If the engine is running with a screech, the candle has a white coating, and the smoke is almost transparent - the mixture is too poor, which threatens to overheat and burn the piston.
Some owners try to save money by buying oils from unknown manufacturers or using working oil. Cheap oil often does not withstand temperature stress, does not burn completely, leaving sticky scoop that cokes and turns into abrasive, which leads to accelerated wear of the cylinder-piston group and the need to replace expensive knots.
Also worth mentioning is the ignition plug error: Installing candles with the wrong potassium number (too hot or cold) can lead to either kalili ignition (when the engine does not stop after switching off) or self-cleaning candles and ignition skips. Always use the candles recommended by the engine manufacturer.
Can I mix gasoline of different brands (AI-92 and AI-95)?
It is technically possible to mix gasolines of different octane numbers, but it is not recommended to do it systematically. When mixing, the octane number is not added linearly (for example, when mixing 1 liter of AI-92 and 1 liter of AI-95 you will not get AI-93.5, the result may be lower due to differences in chemical additives).
How long can you store the finished fuel mixture for a 2T engine?
A standard fuel mixture (gasoline + oil) without special stabilizer additives retains its properties for no more than 2-3 weeks. With the addition of a high-quality stabilizer and storage in a sealed metal container in a cool place, the period is increased to 6 months. After that, the oil begins to precipitate and the gasoline begins to oxidize.
What to do if water gets into the tank?
If there is little water, you can try to pump it from the bottom of the tank through the drain hole (if any), or remove the fuel hose from the sediment filter and drain the water into the tank. If there is a lot of water and it hit the engine, you will need to remove and dry the carburetor, blow the fuel line and replace the spark plugs. In difficult cases, you need a full flush of the tank.
Do I need to change the oil in the gearbox every season?
Yes, the gearbox oil is recommended to be changed once a season or every 100 motor hours, visual inspection: if the butter on the probe or drain is of the color "coffee with milk" (emulsion), then the water got into the gearbox through the coils, which requires immediate oil change and seal seal seals check to avoid corrosion of the gears.
Why does the engine stop at idle speed?
There may be several reasons: contaminated carburetor (idle jicler), improper adjustment of the screw quality of the mixture, air sucking through the gasket of the intake manifold, water in the fuel or too rich / poor mixture.