A lawn mower is a useful technique for mowing grass if you need constant care of lawns and park areas. With its help, you can give a well-groomed look to the grass cover much faster than with a manual braid. The most common gasoline units. That they served without repair for a long time, they need to carry out regular maintenance. One of the mandatory periodic procedures is the replacement of oil. Depending on the design of the internal combustion engine, it is required to use clean fuel or to make a special mixture. Choosing the right oil and gasoline for the lawn mower is of great importance, since the life of the motor directly depends on the quality of the fuels and lubricants.
The function of the oil in the engine of a lawn mower
Two-stroke and four-stroke internal combustion engines are installed on gas mowers. The movement of the knives is provided by the energy transmitted to them from the internal combustion engine. It occurs due to the expansion of gases generated during the explosion of gasoline or fuel mixture in the combustion chamber. In this case, the compression of the gases is provided by the movement of the piston.
For the system to work well, there must exist between mating parts minimum necessary gaps. If their sizes increase due to wear of the working parts, this leads to a deterioration in the operation of the motor unit, and eventually to the complete impossibility of putting it into operation. The problem is that the required pressure is not reached for igniting the fuel mixture mixed with atmospheric air.
Motor oil covers the engine parts with a thin film, this slows down their wear, and also prevents the appearance of scoring on the metal surface of the mating structural elements. This is the main role of oil in the gasoline mower drive mechanism.
The destruction of the nodes caused by friction between the parts does not stop completely, but the use of high-quality materials significantly slows down the process.
In addition to reducing friction between the interacting parts of the internal combustion engine, the use of oil allows you to:
- provide more quality cooling drive unit during operation, improving heat transfer processes between metal and atmospheric air;
- perform work by operating the engine at maximum speed, which increases labor efficiency and reduces time costs;
- protect metal drive gear against corrosion during winter downtime.
High-quality oils reduce the negative effects of elevated temperatures on engine parts. By removing heat, they increase the operating time of the unit to overheat.
Engine oil is a special material that ensures the trouble-free operation of the engine and other systems in the lawn mower. Neglect of its quality leads to various breakdowns of the unit.
Features of two-stroke and four-stroke engines
By the principle of its action, a two-stroke engine is similar to a 4-stroke engine. The peculiarity is only that the stroke of the two-stroke engine is carried out in 2, and the four-stroke. in 4 cycles. The latter refers to the movement of the piston down or up. In this case, for 1 revolution of the crankshaft, 2 cycles occur. The stroke of the piston is its movement, during which the energy of the gases formed as a result of the combustion of fuel is converted into the useful work of the motor (its rotation).
Structurally, in terms of performance, the push-pull and four-stroke ICE models differ from each other according to the following criteria.
- 2-stroke engines have higher specific and liter (about 1.5 ÷ 1.8 times) power.
- By way of lubrication.
- For four-stroke engines, a large fuel efficiency (its consumption is approximately 20 ÷ 30% less), and also their exhaust contains less toxic substances
- The method of supplying fuel mixed with atmospheric air into the cylinder and exhaust gas. In 4-stroke engines it is intended for these purposes. gas distribution mechanism: when necessary, he opens the valves and closes them. In 2-stroke models, it is absent.
- Operating noise level: 4-stroke units are quieter.
- The complexity of the device: 2-stroke models are easier.
- The service life of four-stroke engine models is greater due to an improved lubrication system, and also because the crankshaft rotates at a lower frequency.
- The speed of dialing the maximum speed: 2-stroke units accelerate faster.
- In terms of simplicity of periodic maintenance and in terms of repair, it is easier to deal with a 2-stroke engine. Also, such a motor is cheaper and weighs less than a four-stroke analog.
Power density is the ratio between the power of a drive unit and its mass. Under liter power is understood the relation between power and engine displacement (in liters).
The absence of a gas distribution unit with valves makes two-stroke motors easier and simpler from the point of view of the device. Filling the cylinder with a fuel-air mixture and cleaning it from gas occurs during expansion and contraction through special openings: inlet (purge) and outlet.
Engine differences in lubrication methods
An essential point is the difference in the method of lubricating two-stroke and four-stroke internal combustion engines: for the first, refueling is required not with pure gasoline, but with its mixture in the necessary proportion with oil. It, connecting with air, circulates in the piston assembly, lubricating the cylinder walls, crankshaft and connecting rod bearings, as well as the pistons themselves. When the fuel mixture ignites, the oil, which is included in its composition with the smallest drops, also burns. Combustion products exit as exhaust gas. In practice, two-stroke engine lawnmower oil is mixed with gasoline in specific proportions.
Video: Changing the Makita Lawnmower Oil
There are 2-stroke engines with separate receipt of these components of the fuel mixture, but this more advanced version is not installed on the mowers.
When the motor is 4-stroke, oil served separately, without pre-mixing with gasoline. Practically lubrication is realized thanks to the presence of pipelines, an oil pump, valves, and a filter. The latter is intended to clean the oil from small particles of metal formed during wear of parts.
It turns out that in 2-stroke engines the oil burns out during operation, but in 4-stroke ones it does not, remaining a long period of circulation in the system. Because of this, the requirements for its performance are different. Two-stroke engine oil should leave after combustion the smallest possible amount of soot, and for four-stroke units, it is necessary that the lubricant used maintain its initial physicochemical parameters for a long time.
Suitable 2-stroke engine oil and gasoline
Two-stroke gasoline engines are designed to run on a fuel mixture. Oil change in a lawn mower is not carried out separately. it is proportionally mixed with gasoline. At the same time, only correctly prepared fuel composition should be poured into the motor system.
It is impossible to fill the oil with the principle “the higher its price, the better for the mechanism to work”. Suitable for 2-stroke ICE varieties of oil formulations by the method of their preparation are divided into the following groups:
- semi-synthetic;
- synthetic;
- mineral.
The lubricating properties of the material depend on the base, its ability to remain in the liquid state with decreasing temperature, without significantly increasing the viscosity. The lubricant composition includes approximately 5-15% of various additives. They are intended to increase the practical effectiveness of the product used. Additives allow:
- slow down the corrosion of metal surfaces associated with redox reactions;
- increase the thermal resistance of parts;
- to stabilize the viscosity index of a substance at one level with a change in temperature in a certain range.
The manufacturers of lawn mowers in the instructions indicate the brand of lubricant that is the best option for the unit in operation. If it is problematic to get it, it is possible to change the oil to a similar composition intended for 2-stroke ICEs. Wherein viscosity level must necessarily correspond to the value recommended by the manufacturer of the product.
Gasoline is the main volumetric component of the prepared fuel mixture. Its brand must comply with the recommended in the instructions for use of the mower. From value octane number Gasoline combustion time depends on it: the higher this number, the longer the fuel burns.
If you use gasoline of a higher grade than recommended, then a two-stroke internal combustion engine will fail more quickly.
Fuel mixture
To obtain a fuel mixture, engine oil is mixed with gasoline in certain proportions. They are given in the instruction manual. So, mineral lubricants are mixed with gasoline in a ratio of 1 to 35, and synthetic. 1 to 50.
The mixture is prepared as follows:
- pour the exact amount of gasoline into the canister;
- add, using a dispenser, the required volume of oil;
- close the container with a lid;
- mix the composition, shaking the liquid.
The prepared fuel mixture is simply poured inside the gas tank, using a watering can for convenience.
The proportional ratios between oil and gasoline in the fuel composition are presented in the table below. It will allow you to quickly determine the volume of mixed materials.
You can store the prepared mixture of gasoline with oil in polypropylene or metal containers no more than two weeks. It is impossible to preserve the composition in plastic bottles. This is due to the fact that gasoline reacts with the packaging material, and the resulting products fall into the working mixture. Because of this, when burning the composition will form more soot.
The fuel mixture must only be refilled if the engine is almost completely cold. At the same time, the tank must not be filled up: a place should be left for thermal expansion of the fuel.
It is necessary to observe the rules of fire and personal safety when performing work on the preparation and pouring of the working composition away from sources of fire.
Oil change in 4-stroke engine
In a lawn mower with a four-stroke ICE, pouring gasoline into the tank is required, and the oil in a special hole that is in the crankcase. The operating manual for the equipment from the manufacturer contains information on the frequency of lubricant replacement.
It should be borne in mind that the effectiveness of the lubricant after about 50 hours of operation of the unit decreases. If you need to mow small areas, then in one season, so many working hours are unlikely to be typed. In this case, the lubricant should be changed during the preservation of the device for the autumn-winter period of time.
Change engine oil as follows:
- for about 15 minutes, the engine of the lawn mower is started at idle so that the system warms up, and due to this, the fluidity of the lubricant increases (viscosity decreases);
- unscrew the drain plug located on the crankcase;
- tilt the lawn mower towards this drain, substituting the container in advance to collect the used lubricant (as in the photo below);
- after the mining drains, the cork is screwed into place;
- the mower is installed on a flat platform;
- open the top hole;
- pour new oil suitable for a 4-stroke engine, periodically checking its level with a dipstick;
- when the grease reaches the desired level, the fill hole is closed by tightly screwing the plug.
The volume of material poured is usually 500-600 ml.
For filling into four-stroke ICEs, various types of oil suitable for their operational properties can be used, for example, 10W40, SAE-30. Suitable for most models SF lubricant and higher. Fill for the winter is recommended frost-resistant grease.
Semi-synthetic oil YUKO SEMISYNTHETIC 10W-40
It is not recommended to drain mining directly onto the soil, so as not to contaminate it. You can also use a variety of tools to select a used lubricant. One of the possible options is presented in the photo below.
The process of replacing the lubricant in the wheeled mower’s motor system is fairly straightforward. All operations usually take up to 30 minutes.
It should be remembered that the oil and gasoline for a lawn mower with a four-stroke engine do not mix, but are poured separately.
The best option for both two-stroke and four-stroke engines is the use of gasoline and oil, recommended by manufacturers. Refer to the operating instructions for the mower for instructions on suitable grades. The lubricant must have a viscosity not lower than indicated, otherwise it simply will not be able to perform its functions normally. The gasoline used should not be higher than the brand recommended by the manufacturer because the pistons, valve or rings may burn out. When filling fuel or grease, it is also necessary to observe their volumes given in the instructions. Especially the proportions should be observed when preparing the oil-gasoline mixture yourself.