The following two paragraphs are from the Franks patent #6,544,349 for AutoRX. It doesn't sound natural to me. I have always thought that "natural" meant as it occurs in nature.
"Preparation of a presently preferred synthetic fatty acid ester for use in the method of the present invention is carried out by combining in a suitable reaction vessel about 75 to 80 parts by volume of lanolin fatty acid, about 20 to 25 parts by volume of 2-ethylhexanol, and about 0.2 to 1.0 parts by volume of methanesulfonic acid (or other acid catalyst such as phosphoric acid). The reaction mixture should be blanketed with a slight atmosphere of nitrogen and heated to a temperature of between about 250.degree. F. and 350.degree. F., preferably about 300.degree. F. and 350.degree. F. to allow the esterification reaction to proceed. Water, which is generated in the reaction, is removed using a conventional condenser apparatus as is known in the art. The reaction is carried out for between about 1 to 3 hours or more, until the reaction is completed as determined by monitoring the acid value (AV) of the reaction mixture until a minimum value less than about 12, and preferably less than 10, is achieved. The theoretical yield of the reaction is about 94%.
Thereafter, the reaction mixture is cooled to about 125.degree. F. and the synthetic ester of lanolin fatty acid is optionally blended with (i) an effective concentration of a chlorine-fiee extreme pressure additive composition (generally, about 2%-4% or more by volume), and/or (ii) an effective concentration of a lubricity additive composition (generally, about 2%-4% or more by volume)."