Concerns over corrosive wear risk in cross-head engines led Castrol Marine to question the rigour of some widely used scavenge drain oil analysis (SDA ) techniques. Factors influencing scavenge drain oil characteristics include fuel sulphur level, cylinder oil BN level, system oil contamination and operating profile. Accuracy is critical in SDA interpretation, not least because it supports feed-rate assumptions that are critical to cylinder oil performance, Castrol said. “It is not possible to analyze results accurately without comprehensive knowledge of the fuel oil, the new and used system oil, feed rates and operational data collected from the engine at the time of sampling,” said Paul Harrold, Castrol Marine Technology Manager.