There is still a persistent myth among outboard motor owners, especially older domestic models or Japanese “two-stroke” of the 80s, about the miraculous properties of castor oil. Many old-school water-engines believe that adding castor oil to gasoline saves the engine from bullies, creates an invincible film on the cylinder walls and prolongs the life of the unit in extreme conditions. boat-engine Today, it raises more questions than engineers approve.
To make matters worse, the information on the Internet is often contradictory: some praise thick lubrication for not having soaked up, others complain about the rings being coking up after the first fishing. two-stroke It works by burning the working mixture with the lubricant, and the physicochemical properties of the oil are crucial, and if you plan to use your technique not only for cruising in calm water, but also for serious loads, the choice of lubricating fluid becomes critical.
In this article, we will look at what is going on inside. carburetor And the cylinder in castor burning, why modern synthetic oils have replaced natural oils, and are there situations where castor is still justified, and let's look at the real facts, not the stories from the garage.
What is castor oil and how does it work in an engine
Castor oil, or simply castor oil, is a vegetable oil derived from the seeds of castor squirrel, and its uniqueness lies in its chemical composition: it contains more than 80% of the triglycerides of ricinolic acid, and it is this acid that gives the product high viscosity and excellent performance. lubricating Unlike mineral oils, castor oil does not dissolve in alcohols and does not mix well with hydrocarbons, which is a key feature of it and a major problem.
When you hit a combustion chamber 2T engine Castor oil behaves differently than conventional synthetics, it has a high flash point, but when burned it forms a hard, sticky soda, and this soda is often mistaken for a good lubricant, which is supposed to work and stay on the parts, and in fact, this layer can disrupt the heat sink from the piston, which, when the outboard motor is running at high speeds, can overheat.
Another important characteristic is hygroscopicity: Castor oil actively absorbs moisture from the air. If you cooked the fuel mixture in advance and left it in a can for the winter, by the next season, the tank may have an emulsion with water, which is guaranteed to lead to corrosion. carburetor Mineral and synthetic oils are equally devoid of this disadvantage.
⚠️ Attention: The use of pure castor oil in modern high-speed outboard motors can lead to sticking piston rings due to the formation of lacquer deposits with a sharp change in temperature conditions.
Historical context: why castor was used before
To understand the roots of castor oil, we need to look at the history of engine manufacturing. In the first half of the twentieth century, oil purification technology was low, and synthetic lubricants were a dream come true. Mineral oils of that time were rapidly oxidizing, losing lubricating power, and often leading to bullying of rubbing vapors. vegetable-oilThe s, including castor, were the only alternative that could ensure the survival of the motor.
Castor was particularly popular in aviation and racing cars, and later in outboard motors, and pilots and water engineers valued it for not liquefying when heated and keeping the film where the mineral water would drain from the cylinder walls. Engines of those years had low operating speeds, large gaps in the cylinder-piston group and were designed to work with viscous lubricants. Johnson Soviet Wind It was relevant.
But with the development of metallurgy and the advent of more precise tolerances for piston groups, the requirements for oils changed, mineral-based oils with additives that blended better with gasoline and burned without residue, and Castorca began to gradually lose ground, remaining the lot of enthusiasts of retro technology and specific racing disciplines, where maximum protection is required at short-term peak loads.
Comparison of Castor and Synthetic Oils for 2T
The current market offers a wide range of oils for two-stroke engines, classified according to API and JASO. Synthetic oils are chemically created, allowing engineers to specify their properties. They are easily mixed with gasoline to form a homogeneous emulsion, and burn almost completely, leaving a minimum of carbon, and Castorka loses in this regard, because its properties depend on the seed harvest and the method of pressing.
When you compare the key parameters, you see a difference in approach: Synthetics are focused on engine cleanliness and corrosion protection during long downtime, which is critical for an outboard motor that sits in a garage most of the year. Castor oil, on the contrary, creates a thick layer of loam that can lock rings, reducing compression and power, and synthetics are better at protecting against corrosion because they don't absorb water.
Below is a table showing the main differences between the types of oils when used in an outboard motor:
| Parameter | Castor oil | Synthetic oil (2T) | Mineral oil |
|---|---|---|---|
| Solubility in gasoline | Low, requires stirring. | High, stable mix | Medium |
| Combustion temperature | Tall, forms a solid garment | Low, burns almost completely. | Medium, moderate garnish |
| Bully protection | Very high (at high temperatures) | High. | Medium |
| Impact on candles | Rapid fouling of the insulator | Minimum | Moderate. |
| Storage period of the mixture | Short (absorbs moisture) | Long-term | Medium. |
And you can see from the table that synthetic oils are better at most of the things that are important for the day-to-day operation of the boat. fuel-system and do not require constant cleaning of the carburetor from resinous deposits characteristic of the oxidation products of vegetable fats.
Problems of operation: loam, candles and resinous deposits
The biggest problem that castor users face is the formation of resinous soda. When burned, ricinoleic acid polymerizes to become a solid substance resembling plastic or varnish. This soda settles on the bottom of the piston, the walls of the combustion chamber and, most dangerously, in the grooves of piston rings. Over time, the rings lose mobility, cease to fit tightly to the walls of the cylinder, and the engine loses compression.
The second victim is the ignition system. Ignition plugs They're going to get a conductive or dielectric coating much faster than using high-quality synthetics, and this leads to ignition failures, especially at idle speeds, when the temperature in the cylinder is not high enough to completely burn out the oil residue, and boat owners notice that the engine starts to "trouble" or stop when the gas is discharged.
Also worth mentioning is the resinous deposits in the exhaust system. In two-stroke outboard motors, exhaust is often carried through lower unit into the water. Castor tends to form squishy clumps that can clog the silencer's output holes or even create back pressure to interfere with the gas output. This reduces power and increases fuel consumption.
In which cases the use of castor is justified
Despite all the drawbacks, there are narrow niches where castor oil makes sense, first of all, it's the restoration and operation of retro-motor technology. If you own a 1950s-60s outboard motor that was originally designed to work with viscous oils, and the gaps in its cylinders are large, castor oil can provide better sealing and lubrication than a liquid modern synthetic that will just fly into the pipe.
The second is specific sporting applications, such as karting or some aeromodeling classes, where engines operate at extreme speeds for short periods of time and require maximum thermal stability of lubrication, but even in sports, there is an increasing trend towards complex synthetic compositions based on estro, which combine the heat resistance of castor and the purity of synthetics.
The third option is emergency, and if you're away from civilization, the engine ran out of oil, and the first aid kit or the locals had only a bottle of castork. Adding castor oil in a ratio of 1:20 or 1:25 will help to pull to the baseBut after returning, the engine will require a complete revision, cleaning the carburetor and replacing candles.
Instructions: how to switch from castor to synthetic
If your motor has been running on castor oil for a long time, just pouring synthetics into the tank would be a mistake. A new, more aggressive synthetic liquid could start washing away old resinous deposits that would get chunks into the carburetor or get stuck in the rings. A competent transition procedure is needed to avoid killing the engine.
First, you need to get a defect. Take off the cylinder head and look at the piston. If the coffin is soft and oily, you can try to burn it out or wash it off with special cleaners. If the coke is hard, like coke, you need to clean it. Also check the condition of the coils - the castorc often tans rubber, and after switching to synthetics, the old coils can leak.
Then there's the decoking and washing procedure, and you can use a special mixture of gasoline with a chemical cleaner, and you can let the engine run at idle speed, and then you can replace the fuel filters, because they can accumulate all the washed-out dirt.
FAQ: Frequently asked questions
Can I mix castor oil with synthetic 2T oil?
Technically, you can mix them, but it's not recommended. Castor can precipitate when it comes into contact with some kinds of synthetic base, especially if there's moisture in the mix, which will lead to uneven lubrication and risk of bullying. Better to use ready-made semi-synthetic oils, where the components are already selected by chemists.
What is the ratio of mixing castor into a outboard motor?
For older two-stroke air-cooled motors (chainsaws, motorized units) often pour 1:20 or 1:25. For water-cooled (outboard motors), the proportion is usually 1:40 or 1:50, but due to the low solubility of castor in gasoline, it is better to adhere to a ratio of 1:30 to ensure sufficient lubrication of bearings.
Why does the engine smoke more after castorage?
Castor oil has a high boiling point and does not burn completely, especially in partial load or idling modes. Unburned oil particles are thrown into the exhaust, forming thick white or bluish smoke, which also has a specific sweetish smell.
Does castor damage the rubber parts of the carburetor?
Yes, it can. Although castor is not an aggressive solvent in itself, the products of its oxidation and aging, and the additives that are often injected into it, can cause swelling or, conversely, drying out some types of rubber and polymers used in carburetor membranes and fuel hoses.