(quoted from post at 18:07:02 05/27/15) I have a 720 D that hasn't been started in 20 years and I drained all the old fuel oil out. I know these were designed for #2 fuel oil, but I was wondering if I can burn kerosene? I have an oil furnace in my house and if I can use the same kerosene in my tractor that I use in my furnace , I could save some money. If not kerosene, will the new diesel fuel you buy in gas stations work well in these older motors?
Will it work? Most certainly. Will it save money? Depends. I'm sure that you have done all of the math and analysis about the cost of HHO, off-road diesel, non-taxed kero, the amount of fuel that you expect to burn in the tractor and so on so no point to go there.
At a very high level (like from a 9th grade chemistry class), the "base" (if you will) difference between various fractions of oil is that what we often call kerosene is around C10 to C18 (carbon chain length fractions, more-or-less) and what we often call Diesel is around C16 to C24. The term gasoline is usually around C7 to C12.
None of the common oils are strictly one compound. Consider water (familiar H2O). It is one "thing" (boils here and freezes there, as this or that density). Oils are generally many things of different characteristics. Plain old "gasoline" is composed of many fractions of different characteristics (for example the light ends "boil" at a much lower temperature than the more heavy ends).
Now consider some of the descriptions from (for example) http://donsnotes.com/science/chemistry/hydrocarbon_fuels.html
"#1 Diesel (Diesel 1-D, Kerosene-like, kerosene) - So similar to kerosene that many manufactures make a dual purpose product that is sold as both kerosene and diesel #1."
"#2 Diesel (Diesel 2-D, Home heating oil, No. 2 Gas/Burner oil) - The most common grade, which specifies a fuel that is suitable for most cars and trucks. It is preferred because it has a higher energy content than grade 1-D. However, it does not burn as cleanly or smoothly as a grade 1-D fuel, which is now used in many city busses to reduce smoke in the exhaust and to reduce the odor of diesel exhaust. Winter diesel fuel is #2 mixed with #1 for lower temperature gel point."
In fact number 1 diesel (aka kerosene) is often mixed with number 2 diesel to make it work better in colder temperatures.
some great additional reading here : http://www.chevron.com/documents/pdf/DieselFuelTechReview.pdf