Some great discussion following my original post! As requested, here is a contrast between Renewable Diesel and Biodiesel and Refiner's view of Biodiesel.
Both Biodiesel and Renewable Diesel are produced from the "triglycerides" that comprise animal fats and vegetable oils. Triglyceride is a molecule with three "fatty acid" molecules connected by a glycerol molecule -->
https://study.com/cimages/multimages...lycerides2.jpg
When the vegetable oil / animal fat is processed in a high pressure Hydrotreater in a Refinery, the heat, hydrogen and catalyst used in the Hydrotreater breaks the triglyceride into three separate diesel molecules (that look exactly like a diesel molecule from crude oil) while the glycerin an oxygen portions of the triglyceride are converted to water and LPG (propane/butane) by-products. The "Renewable Diesel" produced has identical properties as diesel from crude oil. This is the Renewable Diesel processing scheme -->
https://www.drdarrinlew.us/sustainab...ss-diagram.jpg
This is a Renewable Diesel / Diesel from Crude Oil molecule -->
https://firmgreen.com/wp-content/upl...l_molecule.jpg
The Biodiesel manufacturing process is not found in refineries as there is no economic justification to construct unique process unit that produces a less desirable product. Biodiesel units are typically "stand alone" units owned by small companies. Biodiesel units uses vegetable oils / animal fats as the feedstock but that is where the similarity to the Renewable Diesel process ends. Biodiesl units use a technology known as "Transesterfication". That process uses Methanol along with catalysts and heat to convert the Triglyceride into three Fatty Acid Methyl Esters (FAME / Biodiesel) and Glycerin by-product). FAME molecules (as do all esters) contain oxygen molecules. This is a good image of the Biodiesel "reaction" -->
http://4.bp.blogspot.com/_yr3xF4J1UV...l+Reaction.jpg
This is a better image of a FAME (Biodiesel) molecule -->
https://www.e-education.psu.edu/egee...files/meth.png
This is a "side by side" comparison of Renewable Diesel and Biodiesel molecules -->
http://https://www.mdpi.com/applsci/...00881-g008.png
Refiners, marketers and consumers "hate" oxygen molecules in any fuel -- gasoline, kerosene and diesel. Reason is, oxygen promotes oxidation and polymerization of the fuel. Oxidation of biodiesel produces acids and aldehydes which can attach components of a diesel fuel system (gaskets, o-rings) and cause metallic components to corrode. The formation of these corrosive products is why Cummins limits the Biodiesel content in a diesel fuel blend to 20% max. Cummins recommends not using Biodiesel in any concentration for pre-2007 engines as the fuel system components are not the proper materials for the acids/aldehydes that form in Biodiesel.
When polymerization reactions occur in Biodiesel due to the presence of oxygen, the polymer products at a minimum will initially cause biodiesel to become darker in color. As the polymerization reactions continue, larger polymer molecules (sludge) forms which can plug fuel filters, fuel lines and fuel injectors.
The oxidation/decomposition/polymerization tendencies of Biodiesel is why we Refiners / Marketers "hate" Biodiesel added to diesel blends provided to customers at the pump. The company I work for purposely limits Biodiesel in diesel blends to 5% max and has never marketed a B20 (20% biodiesel content) diesel product at the pump.
Personally, for my coach I strive to only purchase ULSD which as upto 5% biodiesel content (e.g. the Green diesel sticker on pumps). I avoid whenever possible purchasing B20 (Blue sticker on pumps) to help assure I never have a filter plugging problem.
Since I never know when I'll encounter B20 diesel blend as my only choice, for every fill-up I add Power Service Diesel Kleen to my fuel tank to keep any sludge that may form from plugging filters and injectors -->
https://powerservice.com/psp_product...-cetane-boost/
And when I put my coach into storage, I fill the fuel tank and use both the Power Service Diesel Kleen and Sta-Bil Diesel Stabilizer to help minimizer oxidation / polymerization reactions -->
https://www.goldeagle.com/product/di...el-stabilizer/
Also when my coach is in storage, I add Power Service Bio Kleen to prevent microbes / bacteria "slime" from growing in the fuel tank -->
https://powerservice.com/psp_product...-fuel-biocide/
I know this is a long posting but I hope the forum finds the information useful.