The trend toward upgrading output and efficiency of marine diesel engines, as well as improving their ability to burn heavy residual fuels with high sulfur content, has placed increasing demands on the petroleum industry to improve their products. The oil producers have responded by offering new and reformulated marine lubricants, including highly alkaline cylinder oils to protect against the acidity resulting from the burning of residual fuels, and improved system oils to meet the severe-service demands of the latest engines. The following review is based on data supplied by the major producers of marine lubricants. Free brochures and data sheets giving full details on the formulations and capabilities of these oils are available from all of the producers included in this review. To obtain copies, just circle the appropriate postage-paid card in the back of this issue.
CASTROL MARINE OILS The cylinder lubrication of slowspeed crosshead engines has always been considered an extremely critical area in the field of marine lubrication. This area has become even more critical with modern engines generating very high pressures and temperatures compounded by the widespread use of poor quality fuels.
Almost 20 years ago, engineers realized that uprated crosshead engines would require higher quality cylinder lubricants than those that were available. Because uprated crosshead engines burn more fuel per cylinder unit volume and have a higher tendency to convert the fuel's sulfur into its acid component, engineers addressed the alkalinity of the cylinder oil as measured by Total Base Number (TBN). Over the intervening years, all of the major oil companies conducted extensive R&D programs which showed that indeed alkalinity was the major influence on wear performance. Sporadic use of high TBN products confirmed this fact, yet no oil company took the step of formally launching a higher than 70 TBN oil, largely because such a product could not be made commercially attractive. The Castrol Company was a major groundbreaker in this field. Early in 1989, the company launched its unique Castrol Marine Cyltech 80. This highly successful crosshead engine cylinder oil has a TBN of 80 and contains a unique antiwear additive combination, which offers the shipowner the best of both worlds. The owner can either use Cyltech 80 at the same feed rate as a conventional product and achieve savings through greatly reduced wear of components or he can reduce the feed rate of Cyltech 80 by at least 15 percent and achieve direct cost savings on his cylinder oil bill while still maintaining or improving the wear profile of cylinder liners and pistons. According to Castrol, Cyltech 80 has been in use for over 12 months and consistently exceeded the company's performance predictions.
Castrol reports that cylinder liner wear can be reduced by up to 60 percent and piston ring wear by almost 50 percent.
In an effort to maintain a leading position in the marine lubrication technology field, Castrol has extended its R&D program to investigate the effects on lubrication of high surface temperatures on cylinder liners and piston rings.
CHEVRON Chevron has introduced Chevron DELO Marine Oil 477 for the inland marine trade class. It is marketed as Chevron DELO 6170 Oil for customers on the western and eastern SGsboBrd Chevron's DELO Marine Oil 477 (DELO 6170 Oil) is test proven, demonstrating superior results in the field for today's new generation high-performance diesel engines. This product is designed especially for use in engines for towboat service where some current lubricants may have limited performance and is compounded to a high alkalinity level, measuring 17 TBN (Total Base Number) by ASTM Method D-2896.
New engine designs require improved oxidation and viscosity control for operating demands of fuel efficient engines with higher combustion pressures and temperatures.
Increased alkalinity reserve is required for corrosive wear protection and especially for operations requiring extended drain intervals. DELO Marine Oil 477 (DELO 6170 Oil) was field tested in marine and locomotive service in GE and EMD engines with full approval from these engine manufacturers. Field testing demonstrated increased oxidation and viscosity control compared to typical Generation 4 lubricants. This increased oil control can allow increased drain intervals for GE engines and due to increased drain intervals, the added alkalinity reserve also provides the ability to extend drain intervals. This superior oxidation stability and viscosity control was also demonstrated in EMD engines modified to run at higher operating temperatures to increase efficiency. Chevron DELO Marine Oil 477 (DELO 6170 Oil) provides an optimized engine oil formulation for today's service requirements for industrial engine design in marine towboat and ferry service.
EXXON De-Mar®, formulated by Exxon Company, USA, is reportedly the first zinc-free, high-TBN marine lubricant to pass Detroit Diesel's severe 6V92TA engine dynamometer test. As a result, Detroit Diesel has approved De-Mar 17 for use in main propulsion and auxiliary diesel engines. The approval is based upon the evaluation of wear protection performance and valve guttering protection of the lubricant in Detroit Diesel's two-cycle engines.
According to Detroit Diesel, the acceptable results obtained from its severe 100-hour 6V92TA engine test demonstrated the wear protection capability of De-Mar 17. In addition, the inspection data of towboats operating DDC 8V71N auxiliary engines indicated that De-Mar 17 did not cause valve distress in those engines at the 11,000-hour inspection. Exxon backs its products with the De-Mar 17 marine engine oil limited warranty. This is said to be the industry's first written warranty providing engine repairs if damage is directly caused by the recommended Exxon lube.
As part of a comprehensive inland marine program, Exxon also provides several lubrication services.
The Exxgard® oil analysis program with Exxon's unique "Quickdraw" sampling method helps detect engine problems before they cause failures. Clean, hassle-free sampling makes the Exxgard program convenient to use. Proper sampling ensures consistent, meaningful analyses. Equiptrak Reporting comprises another Exxon lubrication service. The program tracks unapparent long-term operating trends by engine and fleet to promote smarter fleet management. It also flags problem trends so that preventive maintenance programs can be designed. In addition, Equiptrak is cross-referenced to help guide management decisions from personnel to purchasing.
Exxon also provides a marine lubrication chart that recommends appropriate lubes for every need to prevent misapplication. The chart helps to narrow the number of products needed, resulting in inventory cost savings. With the marine lubrication chart, Exxon can design customer lube programs quickly and efficiently.
Exxon offers a comprehensive line of heavy-duty marine lubricants backed by an experienced technical support and marine sales team dedicated to the workboat industry. In addition, Exxon's large distributor base provides convenient access to the marine lubrication program elements.
MOBIL OIL Mobil Oil Corporation's newest lubricants for marine engines include: Mobilgard 570 SAE 50, a superior quality marine diesel engine cylinder oil, is formulated to provide excellent performance in high output crosshead engines with brake mean effective pressures (BMEP) of 16-18 bar and peak pressures of about 160 bar. These highly loaded crosshead diesel engines are operated on heavy fuel oil with high sulfur content in order to reduce operating costs. Concurrently, advances in engine thermodynamics have permitted decreases in specific fuel consumption from 155 to 115 g/hp/ hr.
Mobilgard 570 was developed to provide high load carrying characteristics, improved spreadability, tenacious film retention, and to minimize port and piston deposits. Because of its high alkalinity (70 Total Base Number), it provides better protection against corrosive wear by neutralizing large amounts of strong acids. This oil is compatible with oils normally used in the crankcases of crosshead engines. Mobilmar 300 Series marine diesel engine lubricants are high-ash, zinc-containing oils formulated specifically to withstand the unusually heavy stresses found in high-temperature, low-oil consumption, fourcycle, highly turbocharged engines.
Mobilmar 300 Series oils optimize engine life by assuring outstanding control of varnish, ring carbon, and piston undercrown deposits. These lubricants provide very good water separation and offer a high TBN level (14.7) with excellent alkalinity retention. Their sustained alkalinity provides excellent protection against corrosion when using fuels containing up to 1.54 percent sulfur. Mobilmar 300 Series engine oils are available in two SAE grades: 30 and 40.
Mobilmar 300 Series engine oils are specifically recommended for the Caterpillar 3600 and 3500 Model diesel engines.
Mobilmar 100 Series diesel engine oils are low-ash, zinc-contain- ing lubricants which provide protection against ash deposits and valve guttering. The lubricants offer hightemperature detergency and provide a unique degree of high dispersancy during intermittent, cyclic, and high-idling service, thereby controlling soot and minimizing sludge formation. As a result, their protection of slipper bushings and piston liners against wear is excellent. They also provide excellent valve train wear protection.
Mobilmar 100 Series oils are available in three SAE grades: 30, 40, and 50 to optimize film thickness. These oils meet the low-ash requirements of heavy-duty, twocycle diesel engines.
Mobilgard 450 SAE 40 engine oil is formulated with high quality base stocks which provide low consumption characteristics, high temperature oxidation resistance and thermal stability. These base stocks are combined with specially selected stable additives resulting in an engine oil with well-balanced properties. Its detergent /dispersant qualities result in increased filter life and engine cleanliness levels.
Mobilgard 450 engine oil has proven its superior heavy duty service with fuel oil up to two percent sulfur. Mobilgard 450 has proven its performance in extensive service in engines manufactured by Electro- Motive Division of GM, General Electric, ALCO, Fairbanks Morse, Detroit Diesel, Caterpillar and Cummins.
SHELL OIL With the introduction of Caprinus ® UE Multigrade, 17 Total Base Number (TBN) and Caprinus U Multigrade (13 TBN), Shell Oil now offers two new products for tugs, workboats, coastal tankers, auxiliary power generators and other medium- speed diesel applications.
The 17 TBN Caprinus UE 20W- 40 is formulated for extended oil life in newer, low-oil-consumption engines such as GE's in severe service. Caprinus U has its widest application in EMD diesels and GE engines in less severe service.
According to Shell, compared to the single grade oil now used, Caprinus multigrade oils can cut oil and fuel consumption. This was proven during an 18-month field testing using 16-cylinder EMD diesels. Oil consumption reportedly dropped over 20 percent. In loadbox and dynamometer tests conducted on two- and four-stroke cycle engines, Shell reports a fuel savings of 1 percent.
Shell reports that less wear, better cold starts and extended drain intervals should also accompany installation of Caprinus multigrade oils. When Caprinus multigrade oil is pitted against an SAE 40 grade, Shell claims bearing weight loss is cut almost in half.
Almost all operators want to extend drain intervals between scheduled shutdowns for maintenance.
An oil's ability to do its job over the extended interval is usually limited by one of two things—the loss of grade due to viscosity increase or by exhaustion of capacity to absorb acid by-products of combustion, as measured by TBN. Regarding the viscosity increase, Shell's Shellvis viscosity index improver does an excellent job of grade retention. And the high alkalinity of Caprinus UE (TBN 17), which results from Shell's proprietary detergent technology, should furnish all the acidabsorbing capacity needed for longer drain periods.
Operations with EMD diesels, where long-term TBN management is not as pivotal an issue, will also benefit. Thanks to Shell's detergent technology, Caprinus U Multigrade with a 13 TBN offers a TBN retention comparable to many competitive 17 TBN products.
TEXACO Texaco offers a complete line of quality marine lubricants which are available worldwide to meet the needs of all types of marine equipment. For crosshead engines, Texaco offers TARO Special, a premium quality cylinder lubricant for large, slow-speed diesels burning residual fuels. It is blended from highly refined paraffinic base oils and oil soluble additives to produce a high alkaline reserve (70 TBN) product with good lubricant film strength. It is approved by all of the major crosshead engine builders. It is specially formulated to prevent corrosive wear and minimize ring deposits. Taro Special EX 85 is a premium quality cylinder lubricant specifically developed to meet the requirements of Sulzer RLB engines. It has provided excellent performance in field tests and is approved by Sulzer for those applications where an 85 TBN product with a viscosity of 24 est at 100 degrees C is specified. DORO AR 30 (SAE 30) is a premium crankcase lubricant for large, slow-speed engines. It is blended from highly refined solvent neutral oils and carefully selected additives to produce a moderate alkaline reserve (6 TBN) oil. This product offers unusually good rust and corrosion protection, wear protection and water separation characteristics. DORO AR 30 meets the Sulzer requirement for engines equipped with PTO units.
Texaco offers a complete line of trunk piston engine oils for medium- and high-speed diesels. The specific lubricant required would be based on the sulfur content of the fuel being used in the engine. TARO XD oils, with a TBN of 15 minimum, are used in engines burning fuel with a sulfur content up to 1.8 percent. TARO DP oils, with a TBN of 30 minimum, are specifically designed for trunk type engines utilizing fuel with sulfur in excess of 1.8 percent. TARO XD and TARO DP are available in SAE 30 and SAE 40 viscosity grades. TARO XL 40 (SAE 40) is for use in medium-speed engines where the operating conditions or fuel sulfur content requires a 40 TBN product.
All of these oils are blended from carefully refined base oils fortified with specially developed additive packages to give excellent performance even under the most severe operating conditions. They have been extensively tested both in the laboratory and in the field. TARO XD, DP and XL 40 all offer excellent TBN retention and anti-corrosion properties. They are formulated with selected detergent and dispersant additives which minimize piston ring deposits, improve overall engine cleanliness and provide long in-service life.
Texaco supports its marine lubricants with prompt, efficient technical service and the Texlube used oil analysis program for monitoring the condition of the oils in use.
UNITOR The marketing of fuel treatments by Unitor Ships Service A/S has recently been dramatically strengthened by the acquisition of supplier Gamlen Chemical Company. Unitor marine chemicals are now drawn from the combined resources and expertise of both Perolin Marine, long know for its fuel treatments, and Gamlen Chemical Co. The result is a highly efficient and cost-effective range of fuel treatments, cleaners, and water treatments.
Unitor offers treatment products for such fuel handling system problems as sludge, water contamination, corrosion and bacteria/fungi.
A fuel conditioner such as Unitor's Fuelcare is effective against sludge formation in unstable fuels. The instability can have been caused by aging or long term heating, or by mixing incompatible fuels aboard.
Sludgy fuels often entrain water, thus by dispersing existing sludge and by preventing incompatibility, water contamination can be re- leased for removal by settling/centrifuge. Corrosion is prevented by the filming action of the fuel conditioner. The additive also chemically neutralizes acids in the fuel. Where bacteria/fungi are present, it is first necessary to remove as much water as possible from the fuel and then to treat with a biocide. The biocide Bioclean is a "broad spectrum" biocide, meaning it is effective in killing a wide range of bacteria and fungi, an essential requirement for fuels since exact type of bio-activity is often not known. Water contamination, especially saltwater contamination, in fuel can cause costly problems during combustion, such as high temperature corrosion of engine components by ash deposits. Fortunately, high temperature corrosion and ash deposition problems can be terated with additives such as Burnall or Cleanburn, which are effective in both these areas. With the use of a fuel conditioner these problems as well as storage tank and pipeline corrosion can be avoided.
Unitor also offers Gamabreak, a versatile and effective water demulsifying additive.
VERITAS PETROLEUM Veritas Petroleum Services (USA), Inc., Teaneck, N.J., has been offering a Blend Optimization Program (BOP) to its customers for almost three years. Veritas's experience indicates that many operators in the program were using 50 percent MDO in their BFO. With BOP, they have been able to consistently meet all quality targets using on average only 30 percent MDO.
Without BOP and a fixed blend recipe, blended fuels frequently will exceed one or more specification parameters. According to Veritas Petroleum Services, assuming an $80 ton premia, an operator that uses three tons blended fuel oil per day can expect to reduce his annual fuel costs by about $10,000 per vessel.
Many vessel operators engage in on-board blending of marine residual fuel and diesel fuel to produce a blended fuel for auxiliary engines. This practice became much more prevalent after the substantial price increase for petroleum products in the 1970s. Indeed a variety of commercial blending units are avaialble to the marine operator for this purpose. For operators who do onboard blending the key question is, "How much diesel fuel is required so that the resulting blended fuel meets the auxiliary engine builders fuel specification limits?" Surprisingly, many operators don't ask this question, and fewer still know the answer. Before this question is answered a number of general observations on blended fuel quality and cost are required.
(1) The key quality parameters of a blended fuel are almost exclusively due to the heavy fuel component. Specifically, these include carbon residue, ash, abrasive particles, vanadium and sodium. The MDO component of the blend has a negligible impact on these qualities. The MDO only influences density and viscosity. Viscosity alone is not a quality parameter.
(2) Heavy fuels can vary very widely in all these characteristics. This variation is found between suppliers within a single port, and is not necessarily consistent over time for a single supplier.
(3) It is bad economics to use too much distillate fuel. The cost of blended fuel is directly related to the amount of MDO used. The equation for determining this cost is as follows: Blended Fuel Cost ($ Ton) = HFO price + (% MDO) Distillate Premium/100, where distillate premium is the cost difference between MDO and HFO.
The more MDO in the blend, the higher the price. For example, at $100/ton HFO and an $80/ton distillate premium, a 50 percent blend would cost $140/ton while a 30 percent blend would cost $124/ton.
The operator's objective is to meet the builder's blended fuel spec while using the minimum amount of distillate fuel. To optimize a blend, the operator must know the following: (1) Before blending, the operator should make sure the components are compatible. There is only one way to reliably do this, and that is to mix the actual components and run the appropriate test on the blended fuel; (2) The engine builder's spec limits should be known in order to target qualities for the blended fuel; (3) A complete analysis on the HFO must be obtained; (4) The vis and density of the MDO must also be known.
The following simple example serves to illustrate the above points. Assume that the engine builder's carbon residue limit is 10 percent maximum. For simplicity, let us assume he is blending with clean MDO. To meet the MCR limit of 10, he would require a blend with 41.2 percent MDO if the HFO has an MCR of 17, but only 9.1 percent MDO if the HFO MCR was 11, and 0 percent MDO if the MCR was less than or equal to 10. The answer to the question posed above is that each fuel is different, and so is each optimized blend. •