Man had already been aquainted with oil/had known oil for a long time and used it for various purposes. Just taken out the articles because you are using both man and oil in general terms so no articles. Different has overtones of a change in use so various is preferible.
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AntonijaCan you suggest a better way of putting it?Being acquainted normally refers to knowing a person.
A man had already been aquainted with the oil/had known for oil for a long time and used it for different/various purposes.