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introduced to meet the post-2020 demand for compliant fuel.
Researching the characteristics of these new fuels and how lubricants would need to perform to preserve cleanliness among engines using them allowed this 2020 shift to be pre-empted. This resulted in the development of an additive package specifically for those fuels. When MAN first began discussing its new cylinder oil strategy with lubricant and additive suppliers in 2019, Lubrizol was in the later stages of this development. The more demanding Cat II requirements meant that Lubrizol was working to complete a new product while at the same time investigating how it could be further developed to meet MAN’s forthcoming standards.
Accelerating development of an even higher performance low-base additive package was not an easy task. It had already been discovered that the laboratory tests used to analyse lubricant requirements for conventional marine fuels did not work well with low-sulphur fuels. Bench tests that would usually forecast poor cleanliness performance in an engine were followed by surprisingly good performance in field engines, for example. This challenge was countered by developing new, bespoke tests as well as deploying some tests that had not been used for marine oils before.
It was not just the types of test, but also the way they were sequenced, that helped to secure a new formulation quickly. The accelerated timeframe meant that testing stages had to be compressed, running at the same time rather than one after the other, and dealing with a wider range of candidate formulations at an earlier stage.
Just as the testing of the new Cat II package stood on the shoulders of the IMO 2020 project, so does its formulation. Both formulations have the same low alkalinity, designed for use with low-sulphur fuels. And both feature a balance of detergents and dispersant additives. But higher performance was needed from the Cat II package to keep more modern engines – with higher cylinder pressures and temperatures but lower clearances and tolerances – free from deposits.
As high-performance engines regularly entail high temperatures and pressures, thermal robustness has
20 LUBE MAGAZINE NO.166 DECEMBER 2021
been an important characteristic in any oil for new engines. Increasing the level of antioxidant additives in the mix means that oil is less likely to break down under high temperature and that the oil film is more likely to stay intact for longer, preventing wear and reducing the risk of the oil breaking down and contributing to deposits in the cylinder.
Considering the reports of cylinder scuffing in 2020, the use of anti-wear components has been employed to reduce the risk of these occurrences. These chemistries can widen the window within which a lubricant can protect wearing surfaces, so can provide performance where a lubricant may be operating at the edge of its capability.
The new formulation is a critical milestone as further chemistries necessary for future engine designs and future fuels are explored. Engine design will continue apace in order to deliver greater efficiency for users, and higher performance will be needed from lubricants. Cat II is an important base for this further development.
The same can be said for future fuels, as shipping looks to improve its greenhouse gas impact. Many of the fuels being considered have challenging combustion characteristics and maintaining cylinder condition will be crucial in using them well. MAN’s lubrication strategy is similar for several new sustainable fuels; methanol, LNG, LPG and ethane are all counted as low-sulphur fuels that require Cat II lubricants.
Other options are likely to emerge. Ammonia is one example. Although engines are in development, there is not enough testing data to get an understanding of the implications these fuels will have on cylinder condition. Whatever these new fuels bring, meeting the Cat II challenge allows Lubrizol to develop not just the formulations but also the experience, tools and capabilities to develop new cylinder lubricant solutions even more effectively in the future.
LINKS
www.lubrizol360.com
www.lubrizol.com
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