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.
Synthetic oil requires changing anywhere from 5,000 to 15,000 miles, while drivers generally change traditional oil every 3,000 miles. The length of time between oil changes varies depending on the make and model of cars, along with age and the oil ingredients.