High sulfur levels in fuel, when combined with water vapor, can also cause corrosive wear on valve guides and cylinder liners, which can lead to premature engine failure. The use of proper lubricants and correct oil drain intervals helps combat this effect and reduces the degree of corrosive damage
There is evidence that in some instances, sulfur in gasoline may degrade the performance of oxygen sensors, which may also result in high emissions. High sulfur levels in gasoline may also impair the performance of OBD II systems on some vehicles.
In diesel fuels, a portion of the sulfur content combines chemically with water during the combustion process to form sulfurous and sulfuric acid. The result is corrosive wear that eventually leads to component failure. TBN (Total Base Number) additives in the lubricant protect against high levels of sulfur content in fuel. It is important to know the sulfur content of the fuel because over-inhibiting with high TBN lubricants will result in premature deposit formation. High TBN lubricants are more expensive as well