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Fryer grease - 1985 Mercedes Diesel

I have a 1985 Mercedes Diesel, converted to run on biodiesel. Can I use fryer grease, filtered with a 1 micron filter? Or, do I also need to chemically process the grease, to remove the amino acids?

Which parts in the fuel system (pumps? injectors?) will be damaged by the amino acids?

Thank you!

Forget the “amino acids”…Fry oil must be processed with lye to remove the glycerin before it can be used as fuel. You have more homework to do…

Google ‘greasecar’. Or use Bing if your a Google-phobe.

I Don’t Have A Clue, But Hats Off To You !

I walked by a Ford Pick-Up idling in front of a local builders’ store and the exhaust smell was fantastic ! I thought it smelled like French Fries Or Chinese, but I don’t eat Chinese so I headed immediately to a nearby Taco Bell.

The driver did verify for me that it was running on restaurant waste oil.

Thanks for considering cooking oil, Yum-Yum,

You’re confusing biodiesel with cooking oil. They’re not the same. Biodiesel is a refined fuel. Cooking oil is not.

The amino acids will attack all the seals/hoses in the fuel system. These materials aren’t designed to be exposed to any type of acid. If they were made of viton there would be no problem.

But even if you were to run biodiesel in the engine, you probably couldn’t run anything higher than B10 or 10% biodiesel. Most diesel engine manufacturers don’t recommend running anything higher than B20 in their modern diesel engines. So if a modern diesel engine can’t handle anything higher than B20 which is a refined fuel, what do suppose is going to happen to your 1985 diesel engine when you run cooking oil thru it?


Fryer grease is a molecule composed of 3 hydrocarbon chains attached to a glycerol molecule. You need to break off the glycerol with a chemical reaction.

Many thanks to all the information provided in the replies to my question!

Damn, you guys rock!

Amino acids are not “acids”. They are the base units of proteins. They don’t exactly cut through seals and pipes. While they act as a proton donor in a organic chemical sense, they don’t damage the materials you mention as they cannot chemically bond to them.

To switch over to Vegetable Oil, you would have to convert the MB to run on VO. The oil has to be heated to lower the viscosity so the injection pump can handle it. Some of the setups start on biodiesel or straight diesel and switch over to PVO once the vegetable oil has been heated up to the temperature of the engine coolant.

Yes, I would filter the fry oil at the start. The problem with used cooking oil is that the free fatty acids have to be neutralized and washed out of the desired oil before it can be run in the engine. Thus you would have to process it. If you are at that level, you might as well continue the processing to transesterfy the trigyliceride to biodiesel and wash out the residue.


If you are looking for a challenge and a hobby, go for it. Otherwise don’t plan to save money or travel in your car when others can’t if/when the big hammer drops as there is plenty of competition for waste oil. Google “waste oil furnace” for example.

By the way, there is a large number of gasoline cars available now that get notably better MPG than an older Benz diesel.