The term petrol and gasoline in a 1957 translation from Gauthier's German manual surely refers to the automotive fuels. the English term was "white spirit" otherwise.
Originally Posted by E. von Hoegh
At that time, petrol (as I recall, both grades) contained tetra-ethyl-lead plus other additives including upper cylinder lubricants.
I grew up in my father's auto dealership/workshop and to clean things including small parts they used half/half petrol/kerosine in a high air pressure spray gun.
Flammable and a health hazard (although those guys lived long ! ) it sure got the parts clean and probably left some lube on the surface.
I haven't opened the Prontor SVS here but from what I can see it is not up to the quality of the Graflex Wollensak ones here.