Two Stroke Engine Cylinder Oil Requirements

Due to changes in the sulphur content of fuels that will be required to be used to meet future emissions requirements ship-owners must consider the implications of these changes on two stroke cylinder oil requirements. The current cylinder oil ranges in Base Number from 55 to 100 with 70BN and 100BN being the most common grades able to handle fuel sulphur ranging from 1.0%S to 4.5%S (noting that the use of fuel with sulphur content above 3.5%S is illegal unless an alternative means of emissions compliance is in use). To reduce emission from ships in many cases much lower sulphur fuels will be used in some regions. Operating for long periods (typically in excess of 24 hours) on these very low sulphur fuels will almost certainly result in adverse cylinder liner & piston conditions. 

The purpose of this briefing note is to advise Gulf Oil Marine customers of the details of impending regulatory requirements, the options they have and what actions they should take to ensure optimum cylinder lubrication.

ECA Compliance Regulations

The International Maritime Organization has adopted regulations that have designated certain sea areas as Emission Control Areas (ECAs). In these sea areas ships have to comply with limits to emissions from diesel engines of sulphur oxide (SOx) and nitrogen oxides (NOx).

Currently there are two sea areas that are designated as ECAs.  Along the western, eastern and southern seaboard of North America the coastlines of Canada and the USA include a sea area extending 200 nautical mile offshore which is designated a SOx & NOx ECA (note that the NOx ECA does not come into effect until 2016 and only applies to ships with keels laid from the 1^st January 2016). The sea area to the east of the entrance to the English Channel in the south and coordinates between Scotland and Norway in the north which includes the North Sea and Baltic Sea is designated a SOx ECA.

From the 1st January 2015 ships entering an ECA must reduce the emissions of sulphur oxides to a concentration that is no more than the emissions when consuming a fuel with a sulphur content of no more than 0.1%S.

Current Compliance Options

In regulation 14.4 of MARPOL Annex VI it is stipulated that “While ships are operating within an emission control area, the sulphur content of the fuel oil used on board ship shall not exceed the following limits”. The limit prescribed for after the 1st January 2015 is 0.10%S.

Most ship-owners will comply with the ECA requirements by switching to 0.1%S Gas Oil (ISO 8217 Fuel Grade DMA with 0.1%S max specified). However there are a number of other options that may be adopted to reduce fuel costs.

The currently known options are:

1. Fitting and operating and exhaust gas cleaning system (a wet or dry scrubber)

2. Converting engines to use LNG, LPG or Methanol

3. Procuring one of the new ranges of low sulphur fuels that have recently appeared on the market (Gulf Oil Marine will be providing a briefing document on these fuels).

Cylinder Oil Requirements for 0.1%S Fuel Operation

The majority of Gulf Oil Marine customers will be switching fuels prior to arrival in an ECA and recording the changeover in the ship’s log for Post State Control inspection.

Gulf Oil Marine offers a new cylinder oil to meet the 0.1%S level duty. GulfSea Cylcare ECA50 has been formulated to enable a simple switch over from the customer’s standard GulfSea Cylcare cylinder oil without the need to make any adjustments to the cylinder oil feed rate.

GulfSea Cylcare ECA50 is fully compatible with other GulfSea Cylcare cylinder oils. When changing to a 0.1%S fuel (entering an ECA) the cylinder oil should be switched at the next daily top-up of the cylinder oil day tank. When changing back to high sulphur fuel oil (leaving an ECA) the cylinder oil should be switched on the day prior during the daily top-up of the cylinder oil day tank. By adopting this procedure the cylinder liners will always be provided with sufficient BN reserve to neutralize any acidic conditions.

It is recommended that for those engines where higher cylinder oil feed rates are being used due to cold corrosion problems that the cylinder oil feed rate is reduced to  the recommended average feed rate when using 0.1%S fuel, in accordance with the OEMs federate chart.

Cylinder Oil Requirements for Scrubber Operation

Vessels fitted with exhaust gas cleaning systems will not under normal circumstances be required to change fuel oil in use. Likewise the cylinder oil will not require to be switched.

Cylinder Oil Requirements for Gas & Methanol Operation

Vessels operating on natural gas should use GulfSea Cylcare ECA50. This cylinder oil is suitable for pilot injection using Gas Oil or HFO. 

When a natural gas fuelled engine switches to using 100% HFO for periods of longer than 12 hours the cylinder must be switched to GulfSea Cylcare DCA5070H or GulfSea Cylcare 50100 dependent upon the recommendation in the vessel’s lubrication chart.