Synthetic oil was developed in 1909 by a British firm later known as
Castrol.
The original product moved from aircraft to automobile race courses--known as
Castrol "R". (And known by its distinctive scent).
Following use of the pricey
Castrol "R", I used
"Redline" synthetic oils, as they were the only synthetic oils who advertised at the time: "Made in USA".
Today, all are "blends", so good luck getting a straight answer.
