Higher base number oils launched to address cold corrosion issues

The problem results from, according to one lubricant supplier, Castrol Marine, the high pressures encountered in super-long-stroke engines. This causes higher dew points and increased sulphuric acid formation, which in turn can result in severe corrosive wear. The problem is exacerbated by current ‘slow steaming’ practices, in which the engines operate constantly at low load, and hence at lower temperatures. Heavy fuels with high sulphur content – which are expected to remain in use when operating outside ECAs – only make the problem worse.

Engine designers and lubricant suppliers have recommended cylinder oils specially formulated to neutralise acid formation, particularly for part load conditions when using high sulphur fuels. Castrol was one of the first lubricant suppliers to recognise the problem and introduce a high base number cylinder oil specifically for such engines. The company says that while some other suppliers persisted with mid-range oils, it promoted its Cyltech AW 80 BN product, which was backed up by service letters from MAN Diesel & Turbo and Wӓrtsila.

Most suppliers are now offering high BN cylinder lubricants, and Castrol believes it is once again about to offer a pioneering technology formulated to deliver advanced corrosion control in modern low speed engines optimised for slow steaming. Its Cyltech CL 100 ACC (advanced corrosion control) cylinder lubricant will be launched to the market in May 2014. This, says the company, is a newly formulated 100BN lubricant developed for the latest generation of engines, developed specifically . as a result of Castrol’s early identification of corrosion in these latest engine types when running on higher sulphur content fuels at part load.

The company says that tests, carried out at its technology centre in the UK, have shown significant wear reduction compared to its previous-generation oils. Castrol says that CL 100 ACC is based on new chemistry, and it is confident that Cyltech 100 ACC is the right oil for the right job. The ACC technology contains new surface acting agents, intended to protect cylinder liner surfaces more effectively and for longer periods than older-technology lubricants.

“Revised OEM customer guidance and customer experiences have moved the new engine market decisively in favour of higher BN cylinder oils which Castrol had been promoting for the past two years,” said marketing manager Jonathan Hutchinson.