Mobilgard™ 5100 protects engine using low sulphur heavy fuel oil

The MAN 6S60ME-C8.2TII engine on the bulk carrier, Anna Maria, had been successfully running on heavy fuel oil (HFO) with a sulphur content of 2.58%. An inspection of scavenge port oil samples showed that Mobilgard™ 5100, a 100BN cylinder oil, was providing appropriate engine protection at a feed rate of 0.78 g/kWh. Both residual BN and FE levels were within acceptable tolerances.

The vessel, which is operated by Aegean Bulk, was switched to a low sulphur (0.77%) HFO – this enabled ExxonMobil to test Mobilgard 5100’s ability to protect the engine despite it being primarily designed to operate with high sulphur fuels. The 670-hour test saw the engine slow steam at 50% maximum continuous rating (MCR). The cylinder oil feed rate remained unchanged.

At the trial’s conclusion, Mobil Serv℠ Lubricant Analysis, a state of the art lubricant analysis service enabling marine operators to monitor the health of their engine and lubricant, showed FE content of 15 ppm, down from 63 ppm. It also revealed that residual BN was 58, only fractionally higher than the 51 BN reported when running the high sulphur fuel. Scavenge port inspections showed the pistons, rings and liners were all in good condition. Engine designer MAN Diesel & Turbo attended the end-of-trial inspection. 

Mobil Serv evaluation and an engine inspection showed conclusively that Mobilgard 5100 is capable of providing an appropriate level of engine protection when paired with a low sulphur HFO.

Running a low sulphur fuel with a high BN cylinder oil is typically expected to result in a build-up of deposits that can cause severe wear. However, the trial proved that Mobilgard 5100 can protect against this. It also revealed the potential to save vessel operators money by reducing oil changeovers, simplifying engine operation.