why category II matters for modern engines

As more MAN Energy Solutions’ (MAN ES) Category II performance standard main engine cylinder lubricants come onto the market, one of the first brands to meet that standard provided an opportunity for ship operators and managers to understand from experts, first-hand knowledge of the new marine lubricants available for MAN Energy Solutions’ Mark 9 engines. 

Speaking at a webinar that took place in October 2022, organized by Chevron Marine Lubricants (CML), Simon Chung, Team Lead of the Global Marine Product and Technology support at CML, described IMO’s 2020 sulfur cap on marine fuels as “one of the biggest changes we’ve seen in the industry for years.” The transition from heavy fuel oil (HFO) with up to 3.5% sulfur content to very low sulfur fuel oil (VLSFO) with a maximum of 0.5% sulfur significantly changed the lubrication requirements. 

Simon Chung, 

Team Lead of the Global Marine Product and Technology support at CML

The rise of VLSFO coupled with the drive to lower the carbon footprint of shipping, make lower-ash, lower BN marine lubricants essential for use with such fuels.

“This trend to lower base-number marine lubricants will likely continue,” he predicted, as the industry moves towards lower/zero-carbon intensity fuels alongside some ultra-lower/ zero-sulfur fuels, such as biofuels, LNG, methanol, and ammonia to meet the IMO lower carbon intensity strategy. In line with IMO’s lower carbon intensity strategy, CML has developed its Taro Ultra Advanced 40-cylinder oil, which is a 40 BN cylinder oil that meets MAN ES’ Category II performance requirements. Looking ahead, Chevron plans to have solutions available for the majority of marine engine technologies.

Julia Svennson, senior research engineer at MAN ES, explained the thinking behind its stance on main engine oils, saying that, “MAN ES, unfortunately, found that the lubricants aimed at low-sulfur fuel applications were not able to prevent and manage deposit formation and cleaning, especially in our newer engine types. 

“This risked impeding piston rings, since free movement of the rings is so important for efficient engine operation, we wanted to try to lift the performance of the main cylinder oils,” she said. “Therefore, MAN ES defined its Category I and Category II performance levels to motivate the development and usage of cylinder oils that will suit the engines, the fuels and the environmental requirements of the future,” she added.She acknowledged that alternating between high and low BN oils is a possible solution but said this was effectively “using one oil to clean up after another.”  She echoed Chung’s concern, saying that “Feeding large amounts of calcium carbonate into an engine increases the risk of ash deposits.” This could lead to the buildup in NOx Tier III exhaust treatment equipment, such as EGR and SCR systems. “Reducing the amount of ash in lubricants aimed for low sulfur fuel applications is an obvious step in the right direction,” she remarked.

CML’s Senior Engineer for Marine Lubricants, Luc Verbeeke, told the webinar’s online audience that Chevron’s Taro Ultra Advanced 40 marine engine oil is now recommended not only for use with VLSFO and ULSFO, but also for LNG, methanol, ethane and LPG. “We are further evaluating our options to enable the use of this product with more fuels,” he mentioned. 

“We are not there yet,” he added, “but Chevron is working on solutions.” 

Oil feed rate was among the topics raised by the online audience. Soulis had said during the webinar that a rate of 0.9g/kWh had been maintained for the whole of the test period with Cape Shipping – the same figure the operator used before the trials.

In practice,” there is no specified rate,” Verbeeke advised. “Every engine has its own appetite for lubrication and Taro Ultra Advanced 40 has been tested at 0.6g/kWh on some engines,” he added.

Svennson agreed, saying that, “An engine’s optimal feed rate depends on various factors, including its operating pattern and maintenance.” She advised that, when starting to use a new lubricant, operators should begin with a high feed rate and monitor engine condition while gradually reducing the feed rate. 

It is now available in the Antwerp-Rotterdam-Amsterdam (ARA) range of European ports, in Singapore and Malaysia, with South Korea due to follow shortly after the October webinar. “Over the next couple months, we will be looking to expand the supply availability to other regions, including the Americas and the Middle East.,” Chung said.

Responding to a question from the audience, Elias Soulis, Technical Manager at Cape Shipping, who trialed Taro Ultra Advanced 40 on two of its vessels, explained that the cost of an alternating oil regime compared with continuous use of Taro Ultra Advanced 40 would probably vary from company to company. 

Cape Shipping’s strategy will depend on the price of Category II BN 40 oil at various ports compared with a combination of Category I BN 40 and BN 100 oils. “We have to take into account the complexity of each option and the expected benefit,” Soulis responded.

• This webinar was part of a Chevron Marine Lubricants Insights (CMLi) series of events which will continue during 2023.

Greek ship manager Cape Shipping SA played a key role in testing and approving Chevron’s Taro Ultra Advanced 40-cylinder oil. During the webinar its Technical Manager, Elias Soulis, outlined the companies’ involvement.

• Ships and engines: Cape Pioneer (MAN 8G80ME-C9.2); Cape Corfu (MAN 6G60ME-C9.5) 
• Pre-trial lubrication regime: Alternating between Taro Ultra 40 BN and 100 BN, per MAN ES recommendations. Eight-10 days with 40 BN; three-four days with 100 BN.  
• In-trial lubrication regime: Continuous use of Taro Ultra Advanced 40. Supplies of Taro Ultra 100 were available, but not needed. 
• Checks made: Regular analyses of drip oil samples; visual inspections of the cylinder and scavenge space. 
• Inspections: Two intermediate scavenge port inspections. 
• Outcomes: higher/more advanced piston cleanliness; no abnormal wear or corrosion on the piston rings; liners in maintained condition at the end of the trial.