There are many costs associated with owning and operating an aircraft, and if not properly managed these can become prohibitive. Whether you are a professional pilot, frequent flier or simply fly occasionally for pleasure, having a reliable oil to protect against engine wear and prolong engine life should always be one of your top priorities. The protection high quality engine oils provide can help both minimise the cost of operating and maintenance and reduce overall fuel consumption.
Choosing the right lubricant
For pilots and aircraft owners choosing specific lubricants and oils for their aircraft, the key is to find those products which offer a good balance between price and performance. But how do you tell which one will give you the best performance?
Each aircraft piston engine makes particular demands on its oil. Power plants can be air- or liquid-cooled; two- or four-stroke; geared or direct drive; gasoline or diesel fuelled; or carburetted, fuel injected or turbocharged, so it’s necessary for lubricant suppliers to provide a comprehensive range of oils that are specially formulated to protect a variety of engine types. In addition to engine type, choosing the best performing lubricant will also depend on other factors such as the quality of the lubricant and your flying experience, taking into account how frequently you fly and the operating conditions.
Why are lubricant additives important?
Central to protecting an aircraft’s engine are oils that have anti-corrosion and anti-oxidation properties. Harmful engine corrosion can be caused by using oils that fail to neutralise acids as this allows acid particles to reach metal surfaces. Furthermore, if broken down by heat and acids, these oils could also fail to protect against wear and power-robbing deposits, resulting in an increase in costs and a decrease in TBO.
An engine’s moving parts can also be better protected with anti-scuffing additives. Lubricants that offer sufficient wear protection play a critical role in prolonging the engine life of an aircraft. Oils that do not have a high load-carrying capacity can fail to keep heavily loaded metal components apart, resulting in damaging wear from metal-to-metal contact. Poor lubrication can even lead to excessive wear on cylinders or/and the piston rings and unexpected maintenance costs.
Maintaining your lubricant
While we often discuss the protection that they offer to aircraft, it is important to note that lubricants themselves must be properly maintained to ensure optimum performance. If an oil flows too slowly on start-up, it may fail to reach and protect critical components, leading to high oil consumption and blocked oil-ways, causing oil starvation. The result is expensive damage and in some cases, in-flight shutdown. The low oil pressure that can cause this can develop gradually due to viscosity loss, or when the viscosity of the oil is not suitable for the climate in which the aircraft is being operated. To ensure that the viscosity of your oil is properly maintained, major OEMs recommend oil drain and oil filter change intervals every 50 hours, or every four months for engines fitted with full flow oil filters.
Educating the next generation
Given its importance for aviation in general, maintenance is also a central element of the curriculum for flying schools. When a student undergoes flight training, both the school and the student need to know that the engine is protected all year round, helping the student fly with confidence. For flying schools, having a lubricant supplier with a comprehensive range of approved oils is key to ensuring they meet the needs of each aircraft type.
The importance of innovation
Just as continuous innovation continues to advance aircraft engines, so too must new lubricants formulas and technologies be developed to meet the changing demands of engine specifications.
The 1950s saw the introduction of the first piston engine oils to use ashless dispersants for cleaner engines. Containing non-metallic dispersant additives these oils helped to avoid the build-up of metallic ash residues on critical engine components. The first semi-synthetic, multi-grade aviation oils followed in the 1980s. The grade of an oil – either mono (e.g. W 80, W 100) or multi-grade (e.g. W 15W-50) shows its viscosity – the lower the temperature the plane will be flying in, the lower the viscosity needed. By definition, single grade (e.g. W 80, W 100) and multi-grade oils (e.g. W 15W-50) both meet the same specification –both types of oil are designed to provide excellent service, offering the same rust and corrosion protection.
Multi-grade oils also offer particular advantages for those pilots who fly less regularly or only during warmer months, as they provide protection when the aircraft is stationary for an extended period of time. This means that pilots can be confident that their engine will have total protection from rust and corrosion in between flights and, most importantly, that it will be in pristine condition when they next take to the skies.
In addition, as they remain almost constant as the temperature changes within a particular range, multi-grade oils are able to perform consistently at both high and low temperatures. As a result, they can provide improved operation in extreme temperatures, allowing flying schools and pilots the flexibility to fly throughout all seasons. Maintenance schedules and workshop stock management are simplified by removing the need to change oil between summer to winter grades, and idle time, operating costs and fuel consumption are all reduced when compared with single grade oils.
In the 2000s, the first oil was developed in conjunction with major engine OEMs specifically for light sport, very light and ultralight two-and four-stroke engine aircraft. It was developed to satisfy the specific demands of the small, 4 cycle piston engines used in the light aviation sector, which previously relied on motorcycle oils. The formula that was developed offered improved anti-wear protection compared with the previous generation oil, while also facilitating smooth clutch and gearbox component movement through enhanced protection and lubricity.
These developments underscore the importance of continued innovation in aircraft lubricants, ensuring the availability of high quality products that can reliably meet the demands of the newest aircraft engine technologies.
Article by: Olivier Procès, Former Regional Technical Manager for Europe, the Middle East and Africa at Shell Aviation explains how the use of high quality lubricants can play a critical role in ensuring an aircraft has a long, healthy life. A pilot himself, Olivier has always been passionate about aviation and worked for many years in in the airline industry before he began his career at Shell .