Fuel for waste-oil heater

I know that waste oil heaters are designed to primarily burn used automotive crankcase oil. Some are rather large and meant to heat homes in the winter, but I know a lot of them are simple and home-made and used to heat workshops, barns and small out-buildings. I always see them referenced as being designed to use old engine oil or cooking oil, but I wonder what other fuels they can safely use.

In my shop I run a small business where I rebuild a lot of old automotive steering components. I use a small parts washer to clean the grease and oil from the parts and use mineral spirits as the solvent. After a while the solvent gets dirty and saturated with oil so that the parts no longer dry clean but leave an oily film, so the solvent must be changed.

Can this used mineral spirits be burned in a waste oil heater? I would think it would burn easier and with less soot than engine oil since it is much lighter, and it seems similar in consistancy to old cooking oil. I can’t dump it out and I think that someone may be able to use it as heating fuel, so I will give it away if someone can use it.

I think you need to be careful with this, as mineral spirits are a lot more volatile than what such heaters normally burn (e.g. crankcase oil).

The flash point of motor oil is in the neighborhood of 400 deg F or higher. That of mineral spirits is between 104 to 110 deg F. Do not use mineral spirits in a waste oil heater.