Medium-speed trunk-piston diesel engine oil Shell Argina S4 (formerly )X is a multifunctional crankcase lubricant for highly rated medium-speed diesel engines operating on residual fuel. Argina X is designed for conditions of high oil stress and has been further optimised to improve deposit control. Where fuels with sulphur >3% are in use.
· Rapid neutralisation of acidic combustion products
Gives long-term protection against corrosion of ferrous and ferrous metals.
· Thermal stability and resistance to oxidation
Provides excellent high temperature deposit control and contributes to long oil life.
· Suitability for centrifugal separators
High detergency/low dispersancy formulation releases contaminants and water readily in centrifugal separators.
· Medium-speed industrial or marine propulsion and auxiliary engines, burning residual fuel oils, which create conditions of high oil stress. These conditions usually occur:
- in newer engine designs, less than 10 years old and/or fitted with flame rings,
- where oil consumption is 0.5 – 1 g/kWh
- where load factors are >85%
- where fuels with sulphur >3% are in use
Marine engine reduction gears (SAE 40 only) and certain other ship-board applications, where specialist lubricants are not required.
· Medium-speed engines burning residual fuel need very specialised lubricants. Heavy fuels contaminate the oil with asphaltenes, requiring special types of detergency to avoid sludges. The combustion of high sulphur fuels produces sulphur acids, which cause high wear rates of piston rings and cylinder liners unless neutralised by a high basicity reserve in the oil. The oil is in service for very long periods, so centrifugal separators are used to remove water and combustion contaminants from the oil. Medium-speed engine oils must be specially designed to release these contaminants in the separator.