The most
advanced work with sun¯ower oil occurred in South
Africa because of the oil embargo. Caterpillar Brazil, in 1980, used pre-combustion chamber engines with a
mixture of 10% vegetable oil to maintain total power
without any alterations or adjustments to the engine. At
that point, it was not practical to substitute 100% vegetable
oil for diesel fuel, but a blend of 20% vegetable oil
and 80% diesel fuel was successful. Some short-term
experiments used up to a 50/50 ratio.