Lube-Tech
Figure 2: Lubrizol testing concludes that 40 BN is more appropriate than 25 BN cylinder lubricant for VLSFOs.
Therefore, Lubrizol concluded that 40 BN was the more appropriate BN for <0.5% sulphur fuels as it provides sufficient base reserve to meet OEM guidance with some flexibility for more corrosive engine types and operating conditions, than those experienced in the test engine.
With respect to engine cleanliness, detergents are not the only additives in the formulators tool kit; dispersants are very good at piston cleanliness and have been utilised in heavy duty diesel engines, for example, for many years, but are not commonplace in marine cylinder oils for deposit control.
Dispersants were selected for testing based on known performance benefits they deliver in their existing applications such as deposit control, varnish control and asphaltene handling.
These performance benefits are aligned with the additional performance challenges that <0.5%sulphur fuels are expected to pose to MDCLs compared to current HFOs as identified by Lubrizol’s characterisation of a number of <0.5% sulphur fuels.
38 LUBE MAGAZINE NO.153 OCTOBER 2019
PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.124 page 5
After screening the performance of a number of dispersants in marine bench tests, two were selected for further evaluation in the engine test. These were: a Lubrizol advanced dispersant known to be effective at addressing piston groove deposits and varnish; the Lubrizol novel dispersant that showed improved stabilisation of the commercial VLSFOs in Figure 1.
The Lubrizol advanced dispersant was used to formulate a 25 BN MDCL for comparison with a conventionally formulated 25 BN MDCL. The 25 BN MDCL with advanced dispersant had superior piston cleanliness with lower deposit formation in the piston ring grooves and on the piston lands.
A similar approach was taken for the 40 BN MDCLs. The performance of a conventionally formulated 40 BN MDCL was compared to a 40 BN MDCL that incorporated the novel dispersant. The 40 BN MDCL with the novel dispersant showed improved piston deposit control and piston land cleanliness.
Figure 3: Lubrizol’s engine testing demonstrates a 40 BN MDCL with Lubrizol novel dispersant provides the required level of piston cleanliness performance in a 0.5% sulphur fuel.
The results are summarised in Figure 3. Additionally, the results show the 25 BN MDCL with advanced dispersant showed improved performance over
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