[Nick, also no mention of castor (not caster) oil.]
As I'm sure you are aware, the origin of Castrol. Anyone who has ever smelled burnt castor oil as used in racing cars and bikes until the 1950s will never forget it. Our village in England was near an army base, and occasionally, near the end of WWII, some of the guys would "borrow" a bit of His Majesty's petrol and organize an impromptu grass-track race. They used castor oil, of course, and the utterly distinctive smell is something unforgettable.
At the end of Ken W. Purdy's great book The Kings of the Road, is this passage:
One day a tanker lieutenant in Montgomery's Eighth Army in North Africa came across a bottle of castor oil found in a captured Afrika Corps hospital. He thought of the may happy hours he had spent at Brooklands in the days when only castor oil would stand up to the demands of racing engines. That night he called a few of the faithful to his tent, and had a piece of armor plate brought to red heat with a blow torch. Then a bit of the oil was lovingly decanted upon it, so that they could all inhale the aroma and weep for the bellowing, smoky monsters, the Mercedes and Auto-Union V16s that we will never know again.
