Lubricants. Clean Piston.
Clean piston - It is vital for cylinder oils that have Category II status to have excellent performance, centred on their cleaning ability. ©Chevron

Two-stroke challenge

Chevron supplies first stem of 40 BN Category II lube oil

Chevron Marine Lubricants made its first delivery of a 40 BN Category II lube oil in August, to SIEM Car Carriers. Taro Ultra Advanced 40 has been developed for MAN ES Mk9 and above two-stroke engines.

December 8, 2022

After the IMO’s 0.50% sulphur cap came into effect on 1 January 2020, MAN ES defined two performance standards for lube oils intended for use in its two-stroke engines. Existing oils were dubbed Category I lubes and can be used in MAN ES Mk 8 and earlier engines, but it set a higher Category II standard for Mk 9 and later engines.


With less sulphur in the fuel, lubes with lower base numbers would be needed, but they also had to match or exceed the cleanliness achieved when using typical two-stroke lubes of around 100-140 BN. Until suitable 40 BN oils were developed, MAN ES advised operators to alternate between 100 BN and 40 BN oils, based on scavenge port inspections and its analysis of oil drainage samples.


In April 2022, Taro Ultra Advanced 40 was granted a ‘no-objection letter’ (NOL) by MAN ES, confirming that it can be used continuously, without the need to switch to high-BN lubes. This reduces operational complexity for ships’ engineers and removes the need to carry multiple grades of lube oil.


Chevron Global Marine Lubricants’ General Manager Pat McCloud says: “We have been working with our supply chain to set up blending and supply of the product and it is now one of the first 40 BN category II lubricants to be available in major shipping hubs in commercial volumes.”

He added: “We successfully completed the development of Taro Ultra Advanced 40 and met the MAN ES Category II requirements through thousands of hours of development work in the lab and field testing in collaboration with our technology partner and customers.” A key requirement in MAN ES’ assessment of candidate oils is that they provide the same level of engine cleanliness as high-BN lubes.


According to Chevron the development and approval tests took place on vessels with MAN 8G80ME-C9.2 engine burning VLSFO, but Taro Ultra Advanced 40 is also suitable for use with other low-sulphur fuels, such as ULSFO, LNG and methanol.  The lubricant manufacturer commented: “This versatility is crucial for SIEM car carriers, which will be using the oil in the LNG-fuelled MAN ES 7S60 ME-C GI 12,614kW low-speed engines installed in its 7,500-car capacity sister ships, SIEM Aristotle and SIEM Confucius.”

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