Yes medicinal Castor oil works really well it's more refined and more expensive than what we need. But it will work in a pinch. You can only get it in small containers around here. So it's really expensive to buy enought to mix for fuel.

  This is more or less for the engine "Guru's", isn't medicinal castor also good for engines?
   Seems that a few years ago Charley Melancon and I were talking about this and he commented that "If it's good for us it can't hurt an  engine".
  Charley is now deceased, so I can't go back and check with him although I wish I could...

HI Gil

YOu can use the drug store castor, but you will be much better off if you just buy a qt from SIG  or a nearby Hobby Shop, or a cart racing place may have some

Regards
Randy

The market I work at has 6 oz. Bakers AA for $1.99 a bottle. Mixing smaller amounts isn't that expensive.
Cheerio,Dan

All castor is degummed as part of the initial manufacturing process. Medicinal castor has extra checks as a precaution to ensure there's no ricin poison left in it and may have some sugar added to make it more palatable...ugh. The early Merco instructions specifically warn against using medicinal castor.

AA castor, whether it be Bakers, Castrol M or whatever, just means it's only pressed castor and it's what's called Pale Pressed. #1 Imported (or Industrial castor) is a mixture of Pale Pressed and chemically extracted castor.

Speaking of the old days...

While in Omaha - early 1970's - I visited a (real) railroad repair shop. Noticed that they used Bakers AA Castor, from a big (gallon) red-label can, as release agent on the mold stub when they re-babbited wheel bearings. Asked where they got it. ...A neighborhood pharmacy around the corner from the yard entrance had a deal worked out with them... Their price was even a bit below Sig's at the time.

That's a third of a century ago. Sig still sells Bakers' AA, and no railyards are nearby. If I found one, it'd probably be under tighter security, now, too.