Take careful from fire
Acid rain and global warming are the man two risks using oil as fuel.
pollution
Because when buring oil it produces carbon dioxinde (co2) which causes acid rain.
It will cause global warming
If you are using bio fuel you are not using fossil fuel. Crude oil is a fossil fuel
Burning oil produces a green house gas, called carbon dioxide (co2), which causes acid rain, as well as obviously global warming.
The benefits for using oil as a fuel for transport is it is easy and reasonably cheap to transport the fuel from the source to the destination.
No! Even if it was it would run out very quickly. Using every fossil fuel is bad for the enviroment in some way.
Fossil fuel, oil and gass
The fuel-oil mixture enters the fuel-oil separator. Since the oil is denser than the fuel, by centrifugal separation, it will separate the oil and fuel. the fuel will be on top and the oil will be at the bottom.
If you are not using an "exotic" fuel, I would say 50:1 with a name brand oil.
The 4 stroke Honda outboard is a 4 cycle engine using crankcase oil for lubrication, no fuel / oil mix is required.