More Stories from Castrol Liquid Engineering

Diesels At Sea - No Plain Sailing

Castrol develops effective countermeasures against the destructive by-products in marine diesel engines.

Life at sea for a huge, 10,000+ HP marine diesel and its lubricating oil is anything but easy. Inside each cavernous 100,000+cc combustion chamber, an unfriendly mixture of residues is constantly attacking the exposed surfaces.

Marine diesel fuel oil is ugly, truly offensive stuff. It is only barely refined and is often so crude that it isnít even a liquid at room temperature! It first has to be heated by the ship itself to enable it to be pumped to the fuel system.

A very similar oil was once burned to fire the enormous boilers in the classic steam turbine vessels when they were in vogue. Clearly there was little need to produce a sophisticated fuel for this purpose.

Now that this unimaginable, tar-like substance is actually being used to power internal combustion engines, a whole new set of technical challenges has been presented to lubricant researchers.

To begin with there is the frightening sulphur content in these fuels. A normal diesel truck or car might have to tolerate burning a sulphur content of between 0.2-0.3%. Consider then a sulphur level as high as 4% in the rough and often unpredictable marine variety. The consequence of this is the sulphuric acid by-product that just loves corroding and destroying its host.

Next, the high molecular weight components in this heavy fuel leaves far more contaminants from incomplete combustion. These unwelcome deposits can cause lacquering of piston liners and build-up around rings and oil galleries. Ring-sticking, corrosion, blow-by, increased oil consumption and higher running costs are the results.

Unlike other lubricant suppliers, Castrol technicians have developed a range and choice of oils for this demanding marine engine market. Quite apart from normal consumer products, these complex oils have to possess unique lubrication and protection qualities. Not only do they have to provide an effective defence against normal liner, bearing and piston wear, they must ward off corrosion by neutralising the attacking acids, as well as disperse and eliminate the ominous black asphaltic sludge and insidious piston ring deposits.

Castrolís Cyltech 80 and S/DZ 70 are both front-line products ready for immediate use in the enormous, low-speed, cross-head engines, while TLX is the specified for highly-rated, medium speed, four stroke units.

Many marine operators, it must follow, are already suffering the expensive effects of bore lacquering and piston deposits. For this purpose, Castrol has a potent retro-treatment. Marine DFM has been developed as a patent fuel treatment designed to remove these damaging lacquers. Tests performed on afflicted vessels demonstrated the productís ability to reduce oil consumption and restore performance and economy.