SL2023-737/NHN CyIinder lubrication update for operation on ULSFO, VLSFO, biofuel, LNG, LEG, LPG, methanol, and HSFO

This Service Letter contains guidelines on the recommended lubrication of cylinder liner and piston.
The combustion of very-low-sulphur fuel oil (VLSFO, <0.50% S) and ultra-low-sulphur fuel oil (ULSFO, <0.10% S) in dual-fuel engines has caused a shift in main focus from corrosive wear of cylinder liner and piston rings toward cylinder condition (cleanliness).

The lowered fuel sulphur content and the resulting lowering of the cylinder oil feed rate also stresses the importance of always maintaining an adequate
oil film.
For engines burning high-sulphur fuel, this Service Letter and SL2023-738/IKCA replace SL2014-587. For MC and MC-C engines with Alpha Lubricator Mk. 1 systems, SL2014-587, enclosure 4 should be used

Summary
− Monitor cylinder condition
− Analyse scavenge drain oil
− Ensure clean and free piston rings
− Cat. II cylinder oils for optimal cleaning ability
− Use BN 100 oils or higher for engines showing signs of corrosion