Why do we need synthetics?

The names already make it clear that mineral engine oil is something natural, derived from crude oil, whereas synthetic engine oil is a substance obtained through synthesis. So what created the need for that synthesis, and why did anyone need to invent synthetics in the first place?

The thing is, the conditions any engine operates under are unstable. The engine cools after it stops, warms up after it's started, and while it's running it's constantly shifting its operating mode too — revs, temperature, friction speed and more keep changing. So the ideal engine oil for an internal combustion engine (ICE) would be one whose properties and characteristics stayed constant regardless of the above-mentioned changes in conditions. But that's impossible — any substance thickens when it cools, overheats when friction speed rises, and so on.

So at a certain stage in engine development, the question of ensuring maximum stability of an engine oil's properties across varying conditions became especially urgent. And since a mineral engine oil's base has its own limits when it comes to providing that kind of stability, scientists synthesised molecules to obtain a synthetic base that's far less affected by external factors, with properties that stay far more stable over long-term use.

Synthetic engine oil was first used in aviation, when the need arose to start engines at very low temperatures (-40 and below). Mineral oil simply froze at temperatures like that. Of course, the cost of synthetic oil back then was very high, which ruled out its mass use in car engines. Over time, synthetic engine oils became cheaper to produce and started being used in the automotive industry.