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Originally Posted by rotorwrench

Synthetic oils were found to be excellent for turbine type engines due to their very high flash point (the point where they will actually combust). Turbines operate at extremes that would cause mineral based oils to vaporize and this could lead to combustion. Synthetics vaporize at a higher temperature and they don't combust as easily.

The advent of viscosity building polymer plastics is what allowed the synthetics to be used in a much wider variety of applications. Eventually the synthetics may be the only thing going for automotive use. There is still mineral base oil around now but it's hard to say how much longer it will be available. It's already getting harder to find certain mineral based lubricants due to low demand. I'll keep using it as long as I can anyway.

I have frequently used diesel in turbines when jet wasn't available. In Malaysia it was entirely diesel and boy the exhaust fumes burned my eyes when climbing in or out of the aeroplane. It has a higher specific gravity to Jet, 0.80 compared to 0.75 for jet with variations depending on whether it is winter or summer blended. Jet can be turned to diesel by adding oil. If diesel is used in winter here in Australia, the engine needs to be started in the morning with jet otherwise we get what is a hung start. Diesel has a higher sulphur content and is more corrosive on the power blades. Diesel has more energy than Jet, I see this on the fuel flow when I open the throttle. My town car is diesel and I try to avoid the higher performance diesel when I gas up because it is made by adding lights such as kero. The cheaper fuel (no additives) has more than sufficient performance and provides a slightly better range, or more energy or work in a tank full.
Oh I have not made the point I have in mind. A turbine will, I'm told, burn lubricating engine oil as fuel and thus the comment from Rotorwrench above.