Revisiting Ernest Sweetland,inventor of the Purolator Oil Filter

What little i’ve read about Ernest J. Sweetland sounds like material for an article, book or even a movie.

Does anyone know about this man described as a “basement hobbyist who became a top-flight inventor” and died at age 70 in San Francisco in 1950?

Among his 30 “successful inventions”– one of which was “sleep therapy”– was the Sweetland Cast Warmer, used in hospitals.

He invented the cast warmer after a car accident in which he injured his arm requiring a cast. It took four days for the plaster to dry out. And the experience prompted him to invest in a cast warmer which dried out casts in just four hours, not four days.

His best known invention was the Purolator, once used in cars.

June, I am Ernest J. Sweetland’s great grand daughter. There is a book about him by Dale Z. Kirby called, “Ernest John Sweetland and his Fifty Years of Invention”. It tell’s about his poor childhood, with a drinking cobbler dad, making a camera and other things out of the junk yard as a child, his teen years, education, Nevada Mines, winning over the Irish nurse,making sugar filters in Hawaiia, the amazing 25,000 sq ft home he built for his 7 children in Piedmont Ca, the law suit he won against General Motors in 1938 for his Purolater oil filter, he also played the violin and painted as well as worked secretly for the government during the war. That’s a quick overview of a very interesting life. How did you know of him?? Brenda Smith ~ Calif.


Dear June

 I (belatedly) stumbled  upon your query about Ernest Sweetland. I am the  grand niece of  Ellen Reilly who was Ernest Sweetland’s wife and the Irish nurse mentioned in Brenda Smith’s reply to you. 

 Apparently my dad’s family who lived in Leitrim, Ireland had a ford car and spotted that the sweet filter was being used illegally and informed Ernest who successfully sued Henry Ford. 

That’s really all I know about Ernest Sweetland. 

 Perhaps you can post this on your website in case Brenda Smith would like to get in touch as I’m not sure which of the original sweetland-Reilly family she belongs to. 

 Best wishes



Helen Reilly

26 Woodbridge Road



 t: 0117 971 5539

f: 0117 971 5539

[email protected]

[email protected]