System oils

Setting the new technology benchmark

To design a system oil package with performance equal to or better than those currently available Infineum recently undertook an extensive bench testing exercise. See Tien Tan, Infineum Marine Deployment Technologist, talks about the findings and future developments.

System oils, or circulating oils, lubricate the crankcase in large slow speed two-stroke marine diesel engines typically used in container ships.

The system oil does not need to lubricate the piston rings and cylinder liners in these engines because a separate oncethrough marine diesel cylinder lubricant (MDCL) is used for this purpose.

The requirements for system oils are therefore similar but somewhat simpler than normal trunk piston engine oils (TPEO), which are used to lubricate medium speed four-stroke marine diesel engines. This means that in many cases system oil packages are based on TPEO, which is down-treated to meet alkalinity requirements and boosted with antiwear additives and/or corrosion inhibitors to compensate for the down-treat.

OEM requirements

MAN Diesel & Turbo (MAN) dominates the large slow speed two-stroke marine diesel engine market, holding over 80% market share. Wärtsilä and Japan-based Mitsubishi Heavy Industries are also key OEM players.

Unlike the automotive industry, where performance standards for lubricants are published by industry bodies (e.g. APIACEA or JASO), each marine diesel engine OEM defines the performance requirements for lubricants for use in their engines.