I had a '62 Vauxhall Cresta that used nearly as much oil as petrol.
I've just remembered the first time I ever heard of a sleeve-valve engine. It was in the middle sixties and an article in Motor Sport about the original Daimler Double Six, with a Knight principle V12. Obviously paraphrasing, it's nearly sixty years ago, but it was something along the lines of: "proceeding silently along the road, followed by a cloud (or haze) of blue smoke."