Operating an outboard motor on water is a constant contact with an aggressive environment where salt or fresh water, temperature changes and high speeds create ideal conditions for corrosion and wear. The question of how to lubricate an outboard motor arises for every owner of water equipment, because the right choice is the right choice for the water equipment. grease And oils are a very costly resource, and improper maintenance can lead to a lower unit transmission jamming or the destruction of bearings in just one season.
Many beginners make the fatal mistake of using versatile automotive compounds that are not designed to work in an aquatic environment. marine grease They have a unique chemical composition that allows them to not wash out with water and retain their properties when in contact with fuel. In this article, we will discuss in detail the types of lubricants, their application points and technological nuances that will prolong the life of your “heart” of the boat.
Criteria for the selection of lubricants for water equipment
The main requirement for any lubricant for an outboard motor is the highest water-resistanceUnlike car parts, the parts of the outboard motor are in constant contact with water, which, when heated, turns into steam and can penetrate microscopic gaps. If the lubricant is emulsified (mixed with water), it loses its properties, turning into a kind of mayonnaise, which instantly leads to dry friction and failure of the bearings.
The second critical parameter is adhesion The composition is able to be held on metal surfaces by centrifugal forces, the rotor and the shafts must not be splashed, and for lower unit transmissions, high-viscosity lithium or sulfide lubricants are often used, which provide reliable protection for the gears even under impact loads.
⚠️ Note: Never use graphite lubricants to treat nodes in contact with electronics or sensors, as graphite is a conductor and can cause short circuits in the onboard network.
The temperature range is also important, because the outboard motor can work in hot summers or early springs when the water is still cold, and the quality product must maintain plasticity at low temperatures and not drain when heated to 150-200 degrees Celsius, which is why manufacturers often indicate labeling on tubes. NLGI 2 or NLGI 3, which stands for the viscosity class.
Types of lubricants: lithium, Teflon or molybdenum disulfide?
The market offers many options, but not all are suitable for servicing outboard motors. lithium-lubricantIt has excellent anti-corrosion properties and withstands water contact well, but regular lithium oil can be washed out during long-term immersion, so it is better to choose supplements for lower units.
Lubricants based molybdenum disulphide (MoS2) is ideal for heavy friction knots, such as crankshaft needle bearings and rods, which create a strong film that works even in oil-starved conditions, but these compounds are often black and can stain other knots, so their use should be spot-based and justified.
Special attention should be paid to the Teflon (Teflon).PTFE) additives and sprays: They create a sliding layer that reduces friction and protects against corrosion. Teflon sprays are great for handling external surfaces, gas and reverse control cables, and tilt/trim mechanisms. They do not collect dirt and sand, which is important for moving parts.
Secret Conservation Containment
For long-term engine storage (over 3 months), experienced mechanics use special conservation sprays with a high content of corrosion inhibitors. They create a wax film that reliably protects the metal from oxidation, unlike conventional oils.
Lubrication of lower unit transmission: oil choice and technology
The bottom of the motor, or lower unit, contains a gearbox that transmits the rotation from the engine to the propeller. transmission oilIt must have high anti-bullying properties (often labeled as API GL-5Normal motor oil is not suitable here, as it will not withstand the pressure in the contact patch of the gears.
Replacing the oil in the gearbox is a procedure that must be done regularly, usually every 100 hours or once a season. Before pouring a new formulation, make sure that the old oil is completely drained and has no signs of emulsion (the color “coffee with milk”). If there is water in the oil, then the sealing of the omentums is broken.
The replacement process is as follows:
- 🛠️ Set the boat vertically and warm up the engine so that the oil becomes thinner.
- 🛠️ Unscrew the lower and upper stoppers of the gearbox, giving the workout completely drain.
- 🛠️ Using a special syringe or pump, fill the gearbox with new oil from the bottom up until the oil appears in the upper hole.
- 🛠️ Quickly twist the bottom stopper, then the top stopper, to create a vacuum and prevent air from entering.
| Parameter | Lithium lubricant | Molybdenum disulfide | Synthetics (Polyol Ester) |
|---|---|---|---|
| Water resistance | High. | Medium/High | Extremely extreme. |
| Temperature conditions | 120°C | 150°C | up to 200°C+ |
| Price. | Low. | Medium | High. |
| Application | Bearings, slats | Heavy friction knots | Sports engines |
The biggest mistake when changing the oil in the gearbox is pouring on top. Always fill the gearbox from the bottom up to displace all the air and avoid oil starvation of the gears.
Processing of bearings and slat joints
The screw hub bearings and the slat joints require a special approach, and here the thick lubricant not only serves the function of reducing friction, but also creates a barrier to water. molybdenumIt's a system that prevents the metal from sticking to the metal, and if the slits get sour, it's almost impossible to remove the screw without damaging the shaft.
It is important to not overdo it when servicing bearings. Excess lubrication in closed bearings can cause them to overheat due to foaming of the composition at high speeds of rotation. You need to fill approximately 30-50% of the free space of the bearing, evenly distributing the composition between the rollers.
Pay special attention to omentation. When changing oil or bearings, always check the condition of rubber seals. The oil for omentation should be compatible with the rubber so as not to cause it to swell or crack. Often, silicone lubricants or special formulations based on lithium with Teflon are used for this purpose.
Before assembly, always clean the surface of old lubricant with solvent. Mixing different types of lubricants (for example, lithium and calcium) can lead to a chemical reaction and loss of properties.
Conservation of external surfaces and cables
The outside of the motor is constantly exposed to sprays containing salt, sand and dirt. silicone lubricantsThey create a water-repellent film that easily washes away dirt and prevents corrosion of aluminum alloys.
Gas and reverse control cables are another vulnerable area, and over time, the lubrication inside the cable shirt dries out, the cable starts to catch, which is dangerous when maneuvering, and there are special sprays with high penetrating power to service them that displace moisture and renew the lubricating layer.
Procedure for the handling of cables:
- 🔧 Disconnect the end of the cable from the control mechanism.
- 🔧 Insert the nose of the spray with lubrication into the shirt of the cable and create pressure.
- 🔧 Stretching the cable several times so that the lubricant is distributed along the entire length.
- 🔧 Remove excess lubricants with rags so they don’t attract dust.
⚠️ Warning: Don't use WD-40 pure as a long-term lubricant! it's a light oil solvent that evaporates and washes away quickly, leaving parts unprotected. Use it only to purify and displace water before applying the main lubricant.
Service intervals and seasonal storage
The regularity of the lubrication depends on the intensity of operation. If you ride every Sunday, check the oil level in the gearbox and the condition of the external nodes once a month. For professional use or commercial operation, the intervals are reduced to 50 motor hours.
Before winter storage ("preservation"), a complete revision should be performed, the motor should be treated with a conservation spray, replacing the oil in the gearbox with fresh, this is necessary so that the acidic products of the oxidation of old oil do not destroy the metal during the winter, and it is also recommended to "smoke" the engine through the carburetor (or intake injection) with a special conservation oil to protect the cylinders and the piston group from the inside.
☑️ Checklist for winter preparations
Frequently Asked Questions (FAQ)
Can you lubricate the outboard motor with ordinary solidol?
Solidol is quickly washed out by water, loses its properties when heated, and can coke bearings. Use only specialized lubricants labeled "Marine" or "Water Resistant".
How often should you change the oil in the gearbox?
The optimal interval is once a year before the start of the season or every 100 motor hours. If the leaked oil shows an emulsion (white color), the replacement should be done immediately and check the leakiness of the oal.
What is better to lubricate the screw: thick lubricant or spray?
For the screw shaft and slits, it is better to use a thick water-resistant lubricant (lithium or molybdenum) that can be laid with a syringe. Sprays drain quickly and do not provide long-term protection against boiling.
Will the slurry be suitable for the outboard motor?
The grease for SRUSs often contains molybdenum disulfide and has good anti-sharp properties, but it may be too thick for high-speed bearings. It can be used for slat joints, but for bearings it is better to use specialized marine compounds.