It is genetic - in my family there is no history of it as it is a recessive gene but my mum and dad were both carriers. In Scotland up to 13% of the population has red hair, but around 40% of the population is thought to carry the recessive gene responsible for the world's rarest natural hair colour.
On the other hand, synthetic base oil molecules are chemically controlled, which provides increased ï¬ lm strength and lubricity over petroleum oils. The performance qualities of base oils have a marked impact on the performance qualities of the ï¬ nished product.
There are also semi-synthetic oils, which are a blend of synthetic oils and conventional mineral oils. Semi-synthetic oils are also sometimes called blends. Both types of engine oil are made from crude oil that comes from the ground. The difference is that synthetic motor oils are made from more advanced refining processes and are of a higher purity and quality than conventional mineral oils or semi-synthetic oils.