Rapeseed oil which is also commonly known now as Canola oil has been used as a lubricant for a long time. It was used as an industial lubricant in steam engines and marine applications because of it's tendancy to cling to metal in wet or moist conditions.
It's made from a seed from a cultivated plant that is pressed to extract the oil just like corn oil and soybean oil. The interesting thing about it is that it's a renewable source of oil and possibly fuel and it's biodegradeable. It's relatively non toxic compared to mineral based motor oils although I wouldn't use it in cooking personally.
Cost of production historically has been higher than for mineral based oils and so it hasn't been competitive financially compared to mineral based oil. Maybe now that the cost of mineral based oil is rising, more research into vegetable oils like soy and rapeseed and their modification into suitable lubricants will increase?
Research has been conducted to evaluate rapeseed oil for use as a stable lubricant/base stock oil as a replacement for mineral based oils and as a diesel fuel alternative. It has also been used in biodiesel.
It's quite thin and would need to be chemically modified or need additives to increase viscosity and additives to reduce oxidative degradation if it was ever to be widely used as a motor oil.
At the operating temperature of a gasoline engine it probably would not congeal or thicken significantly in a short period of time, but because it clings to metal surfaces, a residue could possibly linger in the engine which could eventually turn to sludge, but the small amount that would be left behind after a flush would probably be minimal.
Here is an interesting little article about different non mineral oils
web page
and here's another one
web page
[ November 07, 2005, 12:50 PM: Message edited by: stogiedude ]
