More Stories from Castrol Liquid Engineering

Sunlover Cruises To Success On Castrol 

Sunlover Cruises burst onto the Cairns cruise scene as precocious newcomers back in 1991. They had acquired two vessels, The Tropic Sunbird and Tropic Sunseeker, in unusual circumstances. The two luxury Super Cats were built as spectator vessels for the 1986 America’s Cup, but had afterwards fallen into disrepair when run by inexperienced operators.

“We knew very little about the state of the engine internals when we acquired the vessels back in 1990,” said Operations Manager, John Millward “One had even been laid up for quite some time.”

Together with Chief Engineer, John Reeves, the two “new boys” sought some advice and settled on Castrol MLC40 for the expensive, high tech MWM 4 stroke diesels in Sunbird. They chose CRB50 for the two mighty V16 149 Detroits in Sunseeker.

“It wasn’t such a hard decision in the end,” said Reeves “Both manufacturers fully endorsed our choice of lubricants.”

All four engines, and their complement of MWM 6 cylinder auxiliaries, have run flawlessly ever since. With both vessels on gruelling 365 day-per-year schedules, that’s the only way they can afford to run.

“Down time is our biggest fear,” Millward continued earnestly, “not only could we lose as much as $36,000 per day in normal fares, but the damage to reputation would be enormous!”

While Sunlover’s clients enjoy the many pleasures of the Great Barrier Reef, the $500K engines are each catching their breath. They might only run an hour at a time, perhaps just a meagre four hours per day, but when they go, it’s “full steam ahead!”

As with any internal combustion engine, stop-go, heavy load, short haul work takes a particularly harsh toll. Consistent viscosity is critical, as is wear resistance and the ability to avoid gumming and deposits.

The German MWMs are sensitive machinery, making lubricant choice that much more critical. The Castrol Marine MLC range, as chosen for these high output European engines, is an enhanced variation of the established and proven Castrol Marine MPX series of oxidation and corrosion resistant truck-piston engine oils.

The more common two-stroke Detroit Diesels, 149 series in this case, require a monograde SAE 50, especially since they are working in a generally hotter environment. The Castrol CRB range of superior low-ash, heavy duty, fully detergent oils was specifically designed for this make of engine and is fully supported by the manufacturer.

“Castrol, not just with their oils alone, but their entire support network, have made a significant contribution to our success,” asserts Millward “From scratch seven years ago, we’re now the leading carrier out of Cairns.”


Marine diesel operators are faced with the same, sometimes worse, conditions than their land-based counterparts.

Variations in fuel quality, as well as oxidation and corrosion resistance are a high concern.

Despite being tailored to different machinery, both the MLC and CRB ranges address these issues confidently, offering full detergence as well as high tolerance to extreme working conditions.