There’s a thread that may be sort of about boiled linseed oil. I think most of the words in that thread just involve the results of me wandering around looking at stuff on the 'net, but I have no idea whether any of the stuff I found is useful. Anyway, here it is:
At least as to what I wrote in the thread linked above, my advice is that if there’s nothing that shows obvious promise, maybe you shouldn’t waste too much time on it.
Prob’ly better off going with @mad_masala’s recommendation.
Also, in that earlier thread, @JB_IN_TW mentioned Amazon.