Is synthetic motor oil best for your airplane?

While several aviators still ask whether synthetic motor oil is best for your airplane, other industries, such as automotive, are already convinced of the benefits.

In the 1960s, Shell ran several flight evaluations of oil formulated with an all-poly alpha olephins (PAO) base oil. The oil performed very well except in large engines, (turbocharged 520s and 540s). In some of these engines, the oil failed to absorb the lead salts from the combustion process, which in this age have been eliminated with unleaded fuel. This resulted in gray sludge buildup in the ring lands.


In the past there were two main types of aircraft oil used in engines: mineral oil and ashless dispersant (AD) oil. Both types are made of mineral oil - a refined, petroleum based oil.

However, AD oils have added chemicals (additives), which collect debris inside the engine and carry them to the oil filter. However there may now be a synthetic motor oil that is best for your airplane.

Which synthetic motor oil best for your airplane?

There are two different types of synthetic engine oils that are commonly used, but which synthetic motor oil is best for your airplane. The first is a synthetic di-ester, which is a reaction product of an acid and an alcohol. This is pure chemical base oil and is used in almost all jet engine oils. The big advantage of the di-esters is their super-high temperature and low-temperature characteristics. In jet engines it is possible to see instantaneous temperatures of up to 300Deg C, while the lubricant must flow at temperatures as low as 20C. Two of the downsides of di-esters are their cost and the fact that they are very aggressive to many oil seal materials.

Many experts believe that synthetic lubricant base oil, known as synthetic hydrocarbon, synthetic motor oil is best for your airplane. There is, however, some controversy in the lubricant world as to exactly what constitutes a synthetic hydrocarbon. As all hydrocarbon base oils come from crude oil, they need to be refined to improve cold-temperature flow and remove unwanted naturally occurring contaminates, such as sulphur. A commonly used group of oils are known as poly alpha olephins or PAOs.

But which synthetic motor oil is best for your airplane?

The answer really depends on what you fly and where you fly. The advantage to the semi-synthetic oils is the improved low-temperature pumpability, and the high-temperature stability. If you live in a cold climate and have the opportunity to start your aircraft at temperatures below, say, 5C (especially if preheating is not always available), then this synthetic motor oil is best for your airplane.

Two important factors to consider when deciding on which synthetic motor oil is best for your airplane.

There are two other terms that are important in aircraft engine lubrication:

• ASHLESS refers to non-metallic additives. Detergents, on the other hand, are metallic by nature. Detergents may scrub existing ash deposits from an engine’s interior surfaces, which will contribute to the ash content, and possible clogging, of the oil. 
• DISPERSANT refers to the oil’s ability to suspend combustion by-products, keeping them dispersed until the oil is drained. 

While there may be differing ideas about which synthetic motor oil is best for your airplane, there’s no arguing that quality is critical. Habot Oil is a company that is well known for it’s quality synthetic lubricants. Give them a cal to find out more.