Many (more than I like to remember) years ago, we used Castrol R40 in circle track race engines. That was the castor bean based
oil. Does anyone out there remember this stuff? I don't know if it is still available now but it had the greatest smell you could imagine, and we never had engine wear problems. Many of today's lubricants are undoubtedly as good or better. Not a recommendation, just a bit of nostalgia.