MAN cylinder oil service letter shakes up lube market

MAN Energy Solutions has introduced a higher category of cylinder oils.MAN Energy Solutions has introduced a higher category of cylinder oils.

MAN Energy Solutions cancelled NOLs for 15-25 BN cylinder oils and introduced a higher category of cylinder oils in a far-reaching service letter

A service letter published by MAN ES at the end of May is having far-reaching implications for the two-stroke marine lubrication market. In SL2020-694 Cylinder and system oils MAN B&W low-speed two-stroke engines, MAN has introduced a new cylinder oil strategy.

A new category of higher performing cylinder oils, Category II, is being introduced. Cat. II cylinder oils are recommended for MAN B&W Mark 9 engines and subsequent generations.

A subordinate category of cylinder oil, Category I, includes lube oils covered by existing No Objection Letters (NOLs) and is applicable for MAN B&W Mark 8 engines and earlier types.

According to MAN ES, the cylinder oil strategy has been introduced in order to stimulate the development and usage of higher performing cylinder oils for <0.50% S fuels. Such fuels are expected to remain the dominant fuel type over the coming years.

MAN ES’s service experience has identified the importance of maintaining cleanliness of the piston rings and crowns in achieving acceptable time between overhaul (TBO) of the cylinder units. This is a particular focus for MAN ES’s most modern engines, which feature higher pressures and higher temperatures, placing higher performance demands upon lubricants.

Withdrawal of 15-25BN cylinder oil NOL

Alongside the introduction of a new category for advanced cylinder oils, MAN ES has withdrawn NOL approvals from the majority of low BN oils in the market, including some of the best-selling cylinder oils in lubricant suppliers’ portfolios. A few 15-20 BN cylinder oils have retained their NOL status.

MAN ES justified this decision by noting that many of the low BN cylinder oils (15-25 BN) have not met the cleanliness requirements of the newest MAN B&W engines.

While a number of 100 and 140 BN oils have successfully passed through the Cat. II process (see table below), no 40 BN Cat. II cylinder oils are currently available.

Cylinder oil guidelines

The new service letter does not affect MAN ES’s existing cylinder oil guidelines, which the company plans to update later in 2020. The most recent cylinder oil guidelines, SL2019-671 Cylinder lubrication update for 0 to 0.50% sulphur fuels, remain in force.

The focus is on monitoring the cylinder condition and ensure that the piston ring pack is clean and moving freely. In case of excessive depositing, use cylinder oil with a higher cleaning ability (Cat II / BN100).

The alternation time period between high and low BN oils can range from a couple of days to over 300 running hours, as long as the crew make scavenge port inspections, monitor the condition closely and take action if the condition deteriorates.

MAN ES stresses the importance of monitoring the cylinder condition. Drain oil samples should be taken, analysed and evaluated. Action should be taken if the analysis shows deterioration, by e.g. increasing iron content.

Advice for Mark 9 and higher & new-builds

For operators and owners of newbuild vessels and vessels with Mark 9 type engines, MAN ES suggests the use of a Cat. I 40BN and Cat. II 100BN with alternation (if necessary) or with the cylinder oil available as according to the recommendations in SL2019-671.

If the cylinder condition is acceptable when using Cat. I 40 BN oil, there is no need for alternation with a Cat. II 100BN oil. However, if the Cat. I 40 BN oil lacks sufficient cleaning ability, a Cat. II 100 BN oil could facilitate the situation.

0.10% S fuel operation, what cylinder oil to use?

MAN ES notes that a few low BN cylinder oils (15-25 BN) have retained their NOL approval. These can be used according to SL2019-671. Meanwhile, Cat. I 40 BN cylinder lubricants are available and will in many cases be used instead of 15-25 BN products.

As with the advice for newbuilds, MAN ES advises monitoring the condition and in case of deposits, use oil with a higher cleaning ability.

What should be done with 15-25 BN already on-board?

MAN ES is not recommending the costly, time-consuming process of de-bunkering cylinder oil. The ROB lubricants can be used up before bunkering a new cylinder oil. MAN ES recommends that the guidance in SL2019-671 is followed when deciding upon cylinder oils.

Where no issues have been identified, the lube oil can be used as previously. One option might be alternating between low and high BN cylinder oils. MAN ES recommends this for vessels operating within ECA areas on 0.10% S ULSFO continuously. This could also be an option for ME-GIs using <0.1% S ULSFO as pilot fuel.

A third option would be to use Cat. II 100 BN oils. While Cat. II oils will provide the best cleaning performance, the higher Calcium Carbonate content may lead to increased deposits on the crown and after the combustion chamber. If used continuously, it is important to maintain observations for depositing.

Category II cylinder oils





Cyltech 140


Taro Ultra 140

Taro Ultra 100


Mobilgard 5145

Mobilgard 5100

Gulf Oil Marine


Gulfsea Cylcare 50100S

JXTG Nippon Oil & Energy


Marine C1005


Navigo 140 MC

Navigo 100 MCL


Shell Alexia 140

Shell Alexia 100



Sinopec Marine Cylinder Oil 50100

Total Lubmarine

Talusia HR 140

Talusia Universal 100

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