Does oil contain high levels of sulphur?

Oil can contain varying levels of sulfur, depending on its source and type. Crude oil is classified as either sweet, with low sulfur content (typically less than 0.5%), or sour, with higher sulfur content (above 0.5%). The presence of sulfur in oil can affect its refining process and the environmental impact of its combustion. Generally, lower sulfur levels are preferred for cleaner burning fuels.