SECTOR FOCUS: MARINE
Lubricating marine engines in the era of low-sulphur fuels
Ian Bown and Harriet Brice, Technical Managers, Marine Engine Oils, Lubrizol
When the world’s biggest designer of marine engines announced a new standard for cylinder lubrication almost two years ago, the marine lubricant market was thrown into tumult. The requirements set down by MAN Energy Solutions were daunting. To receive a letter of no objection for use with MAN’s Mark 9 engines or newer – and to be included on the ‘Category II’ list - cylinder lubricants would have to show exceptional levels of cleanliness. So far, no low-alkalinity lubricants have been approved.
One lubricant additive package has been approved, however. Lubrizol is the first additive supplier to develop a solution that can meet MAN’s new standards at an alkalinity level (expressed as base number or BN) suitable for continuous use in engines burning low-sulphur fuels. That package is now being deployed in a cylinder oil that is less than 2,000 running hours away from being confirmed as the first to meet Category (Cat) II requirements at BN40.
The changes to MAN’s lubrication strategy are extraordinary. Although Cat II is recommended for Mark 9 and newer engines, it is also suitable for all MAN engines. MAN accounts for well over half of all main engines on ships globally. If that percentage is maintained, Cat II will certainly apply to the majority of all vessel main engines as the fleet is renewed and more new engines enter service.
18 LUBE MAGAZINE NO.166 DECEMBER 2021
A Cat II BN40 product will also mean the end to a messy workaround that has been in place while Mark 9 or newer engines using low-sulphur fuels have not had access to an approved BN40 lubricant. In line with MAN’s advice, those engines have been running on lower performing Cat I BN40 oils but intermittently switching to higher BN lubricants to ensure that cylinders are kept clear of deposits. Having to purchase, handle and operate with two-cylinder oils is an inconvenience for ship operators.
The Cat II specifications may be new, but their beginnings stretch far beyond last year. When the marine sulphur emission control areas (ECAs) came into effect in 2015, MAN already understood that lower-sulphur fuels combined with high-performance engine designs would require different lubrication. In 2014, MAN advised that for engines using 0.1% sulphur fuels in ECAs, they needed cylinder lubricants that focus on cleanliness in the ring grooves and the ring backs.
When the International Maritime Organization (IMO) decided to limit the sulphur allowable in marine fuel worldwide from 2020, it was clear that the baseline for marine cylinder lubricants in general would need to shift. Most ships now use fuels containing sulphur below the global 0.50% limit. Among these is a new type of marine fuel, very low sulphur fuel oil (VLSFO), Continued on page 20
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