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.