If you buy good fuel you should not need anything. Somebody mentioned good old ATF. A quart to 100 gallons or so keeps things clean and lubricated. I would go that route if you are in need of something. The additives that the "snake oil salesmen" are pushing can go up to $125.00 a gallon and better but they tell you a gallon will treat 1,000 gallons of fuel and increase your mileage by 20.0%. Ya, sure and I will respect you in the morning too.
Canola, also known as "rape seed oil" is the oil of choice for deep frying food. Around here I am turning out about 100 gallons of fuel per week made from reprocessed used deep fryer oil. When I say reprocessed, that is what I mean, not just strained and filtered. It is the most amazing stuff. Yes, it cleans out everything in the fuel system of the engine and you will have to change filters a time or two until everything gets cleaned up. But that happens if you start running very high concentrations of 50.0% or so. Start out at lower levels like 10.0% and work your way up. If your intension is to use it for improved lubrication go for a quart or so to 100 gallons of fuel.
I don't know if it ignites quicker than regular Diesel fuel or not, but I have run it at 100.0% in my equipment and it works fantistic. Same power, same consumption or slightly less. Have been using it since 2006 here so have lots of history with it.
Also burn reprocess canola in oil fired furnace in house and just purchased a boiler for in floor heat in my shop.
Now, have got to going looking for more oil supply to make even more.