Sulfur compounds or Sulfates are the indication of the levels of metal sulfates that are contained in the lubricant above the levels normally found in an unused lubricant reference sample.  Metal sulfates are also utilized as part of R&O (Rust & Oxidation) inhibitor packages as well as detergent packages.  Elevated levels sulfate compounds is an indication of burning of the petroleum based product.  As in the case of an internal combustion engine this can result in the formation of deposits in the combustion chamber and the cylinder compression ring wear. These products can be highly acids, create deposits, and accelerate oil degradation.  Additionally, sulfur compounds are highly aggressive toward copper alloys, causing oxidation and corrosion.  Infrared analysis represents a method of accurately measuring sulfur products in used oil. Results are reported on a absorbance scale.

 Sulfur Compounds CAUSE

• Improper scavenge
• Low operating temperature
• Defective seals
• Improper air/fuel ratio
• Abnormal blow-by
• Excessive operating temperatures

 Sulfur Compounds EFFECT

• Accelerated oxidation
• Sulfur compounds introduced into environment
• Acidic by-products formed
• Increased cylinder and valve area wear
• Oil thickening
• Combustion area deposits
• Increased TAN

 Sulfur Compounds SOLUTION

• Increase operating temperature
• Check crankcase venting hoses and valves
• Ensure proper air/fuel mixture
• Perform compression check or cylinder leak-down test

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