MillionGallon® Slow Speed Crosshead Engine Crankcase Oils (System Oils)

MillionGallon QUINQUE® 30 is a slow speed crosshead engine crankcase oil, 5 BN, SAE 30. MillionGallon QUINQUE® 30 has the required main performance features for the Crankcase Lubrication function: Excellent thermal and oxidative stability to minimise oil degradation at high piston undercrown temperatures; Outstanding detergency to minimise the formation of piston undercrown deposits with oil cooled pistons; Good water demulsibility and centrifugibility to enable removal of water and insoluble particulate contamination; Adequate alkalinity to provide protection against the corrosive effects of acidic combustion products; Superior protection against rust and corrosion; High load carrying capability.

MillionGallon QUINQUE® 30 is recommended for the main system lubrication of all low speed crosshead marine engines including the new generation cam-less engines featuring full electronic control such as the Wartsila RT-flex marine engine and the MAN B&W ‘electronic’ marine engine. These technologies depend to a significant extent on shipboard hydraulic systems and for convenience use the marine engine system oil as the hydraulic fluid.

MillionGallon OCTO® 30, a detergent oil with a BN of around 8 for marine engines with oil-cooled pistons requiring a certain detergency level to keep the piston cooling gallery free from carbon deposits, and an R&O (Rust- and Oxidation-inhibited) oil for marine engines with water cooled pistons, to avoid emulsification in case of water contamination.

Over time, improved chemistry allowed for the combination of these properties into one <1–12 BN marine system oil providing adequate detergency and water-separating characteristics.

An SAE 30 viscosity grade is generally applicable for marine slow-speed engine system oils. The viscosity of the oil in service, however, slowly increases over time. This is partly due to ageing (oxidation) of the
oil, but mainly due to the ingress of waste cylinder oil entering the system through leaking piston rod stuffing boxes and recycling of stuffing box drain oil. Along with the viscosity, the base number of the system oil will increase as well. Contamination with high alkaline cylinder oil additives has a negative influence on the water-separating characteristics of the system oil, and increases the risk of bearing lacquering. At a viscosity of around 160 cSt it becomes necessary to take action. It has been common practice to reduce viscosity and base number by diluting the system oil with lower viscosity turbine or hydraulic oil. Oils of different nature, however, may influence the characteristics of the system oil in service.

Consequently, MillionGallon Marine introduced the SAE 20 and SAE 40 version of the standard marine system oil. These grades have the exact same chemical properties, but an SAE 20 grade with lower viscosity is applicable to system top-up or partial replacement.

Besides the marine main engine application, these multi-functional marine crankcase fluids are also suitable for use in certain auxiliary applications including stern tubes and gear boxes. The marine system oil is commonly used for the intermediate shafting as well.

At today’s MillionGallon Marine, twenty-three types of system oils were available for slow-speed marine engine crankcase lubrication. For more detailed information about MillionGallon® marine system oils, please visit our official website @