Motorship 

32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

Reducing marine oil pollution by raising standards in 

marine lubricants

Jonathan Pearce 

Product Manager 

Castrol Marine 
Motorship 

32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

Preserving marine waters 

The world’s oceans cover more than 70% of its surface. At any one time 80% 

of the total shipping fleet is within 400 km of the shore. 96% of surface waters 

have been damaged by human activity, but the shorelines are amongst the 

most vulnerable areas with a large proportion of the aquatic and avian species 

concentrated around coasts and estuaries. Partially enclosed areas like the 

North Sea, with shallow water, restricted water exchange, tidal mudflats are 

particularly vulnerable – and have the highest human populations and hence 

shipping concentrations around them. 

Marine lubricant pollution 

Castrol Marine, which is part of the BP Group, is one of the world’s leading 

suppliers of lubricants. There is growing awareness that lubricants used by 

the shipping industry are leaking or being discharged into the sea. 
Motorship 

32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

Each year, as much as 61,000 tonnes of lubricants are discharged into the 

world’s port and harbour areas. To put this into context, this is one and a half 

times the amount of oil spilled from the Exxon Valdez. 

Increasing focus is being applied to discharges (both accidental and 

deliberate) from the offshore and shipping industries into the marine 

environment. The highest profile is given to emissions and greenhouse gases 

which, together with large oil spillages are brought to the public’s eye by the 

media. The very large number of smaller scale spills and leaks which combine 

to make up the majority of the hydrocarbon discharge into the sea are largely 

unnoticed and unreported, however. 

Since international regulators including the IMO have widely stated the goal of 

'zero pollution' from ships, it is worth considering the extent of operational oil 

pollution from shipping. Shipping causes a wide range of effects on the marine 

environment. Well-known disasters with tankers like Erika (1999) and Prestige 

(2001) come directly to mind. The environmental impacts of classical oil 

pollution are well known with large spills of heavy crude oil smothering sea 

birds and marine life, causing physical damage to marine habitats and toxic 

and bioaccumulative effects throughout the food chain. These accidents only 

form the tip of the shipping pollution iceberg. Most of the harmful emissions 

come from the daily release of various substances. Intentional and 

unintentional discharges of oil, chemical cargo residues, garbage and 

cleaning agents, anti-fouling paint, exhaust and other air emissions and nonindigenous species from ballast water have an ongoing adverse impact on life 

in the world’s seas. 

Marine lubricant spills and releases are much more frequent but smaller scale 

and are less obvious as a result. Many releases or operational discharges are 

not at all evident without close investigation. 

The issue has been raised by various studies, most notably the 2007 

GESAMP report on Estimates of Oil Entering the Marine Environment From 

Sea Based Activities, which found that 457 million litres of oil enter the oceans 

a year from regular shipping activities, and the EMSA CleanSeaNet project, 

which found 4,027 oil slicks in the European waters resulting from regular 

operational discharges. Both studies identified that this pollution was not 

restricted to spillage and leakage from cargoes and observed that the 

operational consumption of lubricants was a contribution to this total pollution. 

Estimates have varied on lubricant loss: basic calculations presented at 

MEPC58 showed 80 million litres of oil-based lubricants are lost annually from 

stern tubes alone. The EU LLINCWA study reported that 15% of all lubricants 

end up in the water (p34). The majority of shipping activities take place around 

our coasts, in or near ports, with the result that lubricant losses can be 

concentrated in these areas. 

Across the world’s seas, each year there are lubricant discharges of as much 

as 224,000 tons of lubricant – with profound effects on water quality and the 

marine ecosystem. 
Motorship 

32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

Lubricant share of marine oil inputs

The amount of oil which enters the sea around ports and harbours from these 

sources is not clear. Castrol Marine has enlisted the assistance of Dr Dagmar 

Etkin of Environmental Research Consulting, Inc. to establish, based upon the 

best knowledge available, levels of lubricant loss into the marine environment. 

Although the focus of the press is always on the big spillages, these make up 

a small proportion of the total amount of oil going into the sea. The very large 

number of small spills and releases which arise from day-to-day shipping 

operations make up more than half of the total amount of oil which pollutes the 

sea. 

This work is not yet completed but these initial findings show that the ultimate 

fate of significant amounts of oil is currently unknown. 

The Etkin report provides estimates of lubricant discharge, leakage and spills 

in the world's ports from shipping activities, but excludes land-based 

contributions to these. The principal findings are: 

In 1.7 million visits by vessels to the world's ports, there are 924,000 litres of 

lubricating oil going into the sea from recorded spills. Oil pollution from other 

lubricant loss from other areas of vessels (including hydraulics, gear oils and 

greases) amounts to 32.3m litres of oil per year. 

Oil consumption from stern tubes in normal operation is not monitored and the 

majority of oil consumed is released past seals into the sea. This has been 

determined to be somewhere between 4.6 and 28.6 m litres per year. 
Motorship 

32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

Total lubricant loss from operational discharges is estimated at between 38m 

and 62m litres – approximately one and a half times the size of the Exxon 

Valdez oil spill. 

Sources of lubricant pollution

Spills and releases come from a number of different sources on a vessel and 

it is worthwhile considering the two separately. The diagram shows a typical 

vessel with its major systems identified. Focus in the past has always been 

upon the highly visible spills which take place, with hydraulic fluids being the 

primary area of concern. This is not a surprise as these systems operate at 

high pressures and high flow rates. They incorporate elastomer seals and 

flexible hoses which are subject to wear and abrasion, and also to fatigue with 

continual pressure fluctuations. When a hose burst occurs there is a 

significant amount of oil released onto the deck and then onto the sea, where 

its presence is very obvious. Similarly leaks from smaller items of deck 

equipment such as winches and windlasses are very evident. The gearboxes 

on this equipment are not generally pressurised, but leaking seals on shafts 

result in gear oil leakage onto the deck and again it makes its way over the 

side. These occasional spills or leaks are easily evident because they result in 

an oil sheen on the water surface – in port, at least. 

There are a number of systems situated below the waterline which require to 

be lubricated also. The main ones to consider are the stern tube bearing, 

thruster gearboxes and horizontal stabilisers. All of these have pressurised 

lubricating oil systems where the pressure is maintained at a higher pressure 

than the surrounding sea. The reason for this is to ensure that no significant 

amount of water enters the oil system, where it would compromise the 

reliability of the unit. The corollary is that any leakage which does take place is 

from the unit outwards into the sea. When the elastomer seals on propeller 

shafts or thruster bearings are in good condition this is a small (but 

continuous) amount of leakage, but any seal wear or damage increases the 

amount. The lubricant is released well below the waterline into an area of 

turbulence (the propellor) which means that it is immediately dispersed and no 

giveaway sheen occurs on the water surface. 
Motorship 

32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

Stern tube leakage varies by vessel type, but has been conservatively 

estimated to be 2.6 litres per day based on empirical data on lubricant 

consumption. This ranges from 20 litres a day with barge carriers to 2 litres for 

smaller vessel types. 

Average per-port visit inputs from deck-based machinery are estimated at an 

average 1.2 litres per vessel. Average per-port visit inputs from in-water 

machinery sources are estimated to be about 8.6 litres per vessel per port 

visit. The highest rates of input coming from ro-ro cargo, ro-ro 

passenger/cargo and general cargo ships. By using lubricants with increased 

biodegradability, the costs of clean-up could be reduced to between US$ 30-

32 million annually. 

What are the drivers for green behaviour?

Shipping has a integral role in transporting people and goods all over the 

world (90% of manufactured goods are shipped by sea at some point in their 

distribution). In terms of emissions per tonne per kilometer, marine shipping is 

one of the most environmentally responsible methods of transporting goods. 

However, because of the scale of the industry, its overall impact is substantial. 

There is far greater awareness of environmental issues today in the general 

public. Thus customers and regulators demand higher standards. And this 

means technologies are being developed to meet a growing demand for 

sustainable shipping. Most of these revolve around emissions and ballast 

water issues, with the oil discharge component still being the primary focus 

from bodies such as MARPOL. 

In Europe, the Classification Societies such as Lloyds and DNV are 

introducing environmental standards, and other bodies like the Clean Shipping 

Index have come into existence, which offer a voluntary code of practice and 

accredition to a voluntary environmental standard. Only in the USA is there an 

admission that regular releases of oil take place in normal operations. Recent 

updates to the Clean Water Act in the US require all ship-source discharges – 

including lubricants - to be monitored and reported on a regular basis: 

EPA Vessel Permit Rule: 2.2.9 Controllable Pitch Propeller and Thruster 

Hydraulic Fluid and other Oil to Sea Interfaces including Lubrication 

discharges from Paddle Wheel Propulsion, Stern Tubes, Thruster Bearings, 

Stabilizers, Rudder Bearings, Azimuth Thrusters, Propulsion Pod Lubrication, 
Motorship 

32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

and Wire Rope and Mechanical Equipment Subject to Immersion. 

Owner/operators should use an environmentally preferable lubricant, including 

vegetable oil, synthetic ester, or polyalkylene glycol as a base for these 

applications when feasible. Use of an environmentally preferable lubricant 

does not authorize the discharge of any lubricant in a quantity that may be 

harmful 

In Europe the focus on marine lubricants environmental effects is being 

raised. The European Ecolabel for lubricants scheme is under review, to 

extend its jurisdiction to lubricants in marine applications. 

How do we measure environmental performance? 

Marine shipping does not currently need to comply with a great deal of 

legislation of the substances used on board. The offshore oil and gas industry, 

however, is very highly regulated, particularly in the North Sea. A great deal of 

attention is given to the chemicals used on and discharged from an offshore 

installation used either for exploration drilling or for long term production. 

Some of these, such as well chemicals, are deliberately discharged in their 

normal use. Others are assessed as the risk of discharge or spill is considered 

to be high because of the equipment in which they are used. The standards 

for environmental compliance which are defined within the OSPAR HMCS 

regulations which apply to the North Sea are being adopted by most other oil 

and gas regulators around the world as they are considered to be the most 

appropriate to measure the overall impact of a substance – not just its 

persistence. Individual components within the formulation are tested to 

determine their toxicity, with testing on four different species at different 

trophic levels in the marine food chain, plus bioaccumulation potential and 

biodegradation tendency to determine their persistence. These results are 

taken together with the likelihood and scale of a potential release to fully 

document the impact upon the environment around the area of operations. 

Toxicity of the lubricant and its components (the performance additives within 

it, particularly) is likely to be a more significant issue for lubricants which are 

discharged below the waterline rather than those which are spilled onto the 

water surface. The lubricant will be emulsified and dispersed within the water 

column and will be more readily available to organisms within it as a result. 

Because of this consideration, the OSPAR assessment criteria are the 

standard of environmental performance which Castrol is working towards for 

lubricants supplied to both the offshore and marine markets. Although these 
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32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

regulations do not cover the shipping industry, they are considered the most 

appropriate standards to measure the impact of released chemicals. 

Environmentally responsible lubricants 

Apart from the frequency and volume of pollution arising from the use of 

lubricants on board ships, the composition of the pollutants is very different 

from the large crude oil spills which are generally considered. Lubricants are 

manufactured from highly refined base oils with functional additives present in 

order to give the required performance properties to suit the intended 

application. These may enhance the oxidation stability of the oil, increasing its 

service life; they may improve protection against corrosion, improve the load 

carrying properties or prevent the oil foaming in service. Other dispersants or 

detergents may be present in order to suspend contaminants, whilst other 

additives can be used to cause the oil to emulsify or separate water, 

depending upon its usage. The level of additives present can vary between 

less than 1% in basic lubricants up to 30% in some complex formulations. 

Because of the focus on spills, and the larger ones at that, the effects of these 

additives in the marine environment are not normally assessed. Even when a 

user wants to be “environmentally friendly”, he is most likely to look to source 

a “biodegradable oil”, which may well be formulated expressly to biodegrade 

but with no thought given to the toxic effects of additives upon marine species. 

Lubricant additives are often strongly surface-active and stable organic 

compounds, which means that they have a strong potential to be toxic and to 

bioaccumulate. Because it is possible for additives in oils which are dispersed 

in the sea to migrate into the water phase, the toxicity of individual additives 

needs to be considered as well as the results of the formulation as a whole, in 

order to determine what the effect will be of discharge into the marine 

environment. 

It is worth mentioning the special case of stern tube lubrication as this is 

probably the largest volume of oil entering the sea. Stern tube lubricants are 

simple products formulated from highly refined base oil plus a proportion of a 

fatty oil to make the lubricant emulsify and to improve lubricant film strength 

when water is present. It is common practice, however, to utilise the main 

engine oil as the stern tube lubricant in order to minimise the number of 

lubricants held on board. The engine oils are the correct viscosity and their 

formulation means that they will also emulsify water in the same way. 
Motorship 

32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

However the additives can be up to 30% of the formulation and are strongly 

alkaline in order to neutralise the acids formed during the process of fuel 

combustion. Because the lubricant is supplied for the vessel’s main engines, 

the amount which is used in stern tubes and released to the sea is not 

recorded. 

Castrol Bio Range. 

We decided to develop a new lubricant range based on the fact that lubricants 

are chemicals that are going to end up in the sea. This is the first time this 

approach has been taken to marine lubricants. And we are proud to offer our 

customers the leading technology in the industry. We have done this without 

compromising on our commitment to high performance products for our 

customers. 

If we accept a shorter service life than would be given by a conventional oil, 

we may reduce the impact of a spillage but have increased the amount of oil 

consumed along with its attendant packaging, shipping, storage and disposal 

costs – all at a cost to the environment we are trying to protect. 

We have found the perfect balance so that the new range meets all major 

national and equipment manufacturer’s standards. Our new products are also 

compatible with existing components and standard oils. This means retrofitting is simple and straightforward with no risks during change-over. 

Castrol has taken the lead in providing a solution to the marine industries in 

minimising sea pollution through launching the world's first comprehensive 

range of more environmentally responsible lubricants. The performance of 

these new fluids as lubricants is in no way compromised by their improved 

environmental characteristics. This would be totally unacceptable to the end 

user as it would at best give reduced equipment availability through increased 

maintenance requirements and at worst could compromise safety or even 

affect the overall environmental impact of operations – the very thing we are 

seeking to improve. These products give a viable alternative to companies 

that want to cut their impact on the world's marine environment. 

The Castrol range of environmentally responsible lubricants has been 

formulated to have a reduced environmental impact when compared to 

conventional lubricants – giving demonstrable benefits in the following key 

environmental performance criteria: 

Superior biodegradation. 

Significantly reduced bioaccumulation (using OSPAR criteria for assessing 

bioaccumulation potential) and toxicity. 

Enhanced renewability. 
Motorship 

32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

The Castrol Bio Range range of environmentally responsible lubricants is 

comprised of: 

Castrol BioStat – Stern tube and thruster lubricant. 

Specifically developed for stern tubes. 

Is readily emulsifiable, allowing 20% water absorption without compromising 

lubricating performance. 

Provides better protection of bearings and gear components (when compared 

to conventional mineral oils) to help avoid unscheduled inspections and 

repairs. 

Castrol BioBar – Hydraulic fluids.

Extended life (up to 50%) proven in long field experience. 

High viscosity index and low pour point: 

Allows start up at low temperatures. 

Provides thicker lubricating film and therefore enhanced component protection 

at high temperatures. 

Gives excellent wear and corrosion protection, providing long term machinery 

protection. 

 

Castrol BioTrans – Gear lubricants.

Long term machinery protection (up to 25% life extension of gear teeth). 

Oil life extended up to 100% when compared with conventional mineral oils. 

High viscosity index and low pour point: 

Allows start up at low temperatures. 

Provides thicker lubricating film and therefore enhanced component protection 

at high temperatures. 

Gives additional anti-wear protection. 

 

Castrol BioTac EP2 – Grease.

Water spray-off resistance reduces frequency of application (and extends wire 

rope life). 

Good pumpability at low temperatures (operating temperature range from -

35o

C to 120oC) facilitates use of pressurised lubrication equipment. 

High load carrying capacity and anti-corrosion properties protecting equipment 

and adding value. 

 

Conclusion 

Marine contractors of all types are operating in a global marketplace and have 

identified that good environmental performance and demonstration of their 

Corporate Social Responsibility is a key to successfully marketing their 

services. Many have accepted that they need to go beyond the minimum 

standards required by legislation, but there is as yet a great deal of lubricant 
Motorship 

32nd Propulsion & Emissions Conference 

Hamburg 

28th & 29th April 2010 

egress into the coastal environment which is not quantified, with no measure 

of the environmental impact of these marine operations currently in place. 

The replacement of conventional mineral oils with environmentally responsible 

lubricants in equipment where there is a risk of accidental spillage or leakage, 

and consequent environmental damage, could eventually become mandatory. 

The harsh reality is that environmental legislation can only get tougher but 

ships will still continue to leak oil. Use of environmentally responsible 

lubricants can help counter this dilemma. Until legislation is in place, there is 

likely to be slow adoption of environmentally responsible lubricants unless the 

vessel operator has a particularly high public profile – cruise ship operators 

and ferry companies, for example. Other encouragements to use these 

products could be put in place such as reduced port fees for ships adopting 

higher environmental standards. The technology to give a major improvement 

in environmental performance is available now, for those shipping operators 

who want to make a difference now - instead of waiting until irreversible 

damage is proven in the marine environment and legislation is introduced to 

force their adoption.