Optimising lubricant spreadability with Gulf Marine

This fundamental requirement is reinforced in CIMAC Recommendation No. 15 (Guidelines for the Lubrication of Two-Stroke Diesel Engines), which highlights that effective distribution of cylinder lubricants across the liner surface depends on their viscosity, ability to wet the metal, adherence, and capacity to form a coherent film.

With this in mind, Gulf Marine recently conducted a focused spreadability study to better understand how viscosity and additive content influence the wettability of cylinder lubricants on stainless steel surfaces. Using contact angle measurements – a standard method to assess how well a liquid spread over a surface – the study evaluated both formulated marine cylinder oils. The tests were performed using a Ramé-hart Contact Angle Goniometer on stainless steel substrates, which more closely resemble the material of engine liner surfaces.

One key finding was the influence of viscosity on spreadability. As shown in Figure 1, lower viscosity oils, such as SAE 30 and SAE 40, consistently dropped to lower contact angles more quickly than higher viscosity SAE 50 oils, indicating more rapid and effective spreading.

Among formulated lubricants, Gulf Marine’s Category II 40BN SAE 50, GulfSea Cylcare XP 5040, exhibited an initially high contact angle but dropped sharply, suggesting fast spreading. This enhanced spreadability is likely due to the presence of polar additives such as Antiwear, which improve the oil’s ability to adhere to and wet metal surfac

Gulf Marine has also performed benchmark tests comparing the spreadability of lubricants with varying additive formulations revealed notable distinctions. While classical 40BN and 70BN SAE 50 oils maintained stable and higher contact angles over extended durations—indicating consistent surface behavior—GulfSea Cylcare XP 5040 exhibited significantly enhanced spreading performance. These findings highlight the evolving role of advanced additive chemistry in influencing wetting dynamics.

Together, these results reinforce the importance of additive-engineered solutions in tailoring lubricant behavior beyond what is naturally afforded by viscosity alone—offering opportunities to unlock higher efficiency and cleaner performance in today’s marine engines.

Key conclusions from the spreadability study include:

• · Lower viscosity oils exhibit better spreadability on stainless steel surfaces.
• · CAT II 40BN SAE 50 oil, GulfSea Cylcare XP 5040, spreads rapidly.

 This research highlights Gulf Marine’s commitment to advancing lubricant technology. Insights from both the spreadability and bench wear studies will guide the development of next-generation cylinder oils that meet the evolving demands of modern engines and stricter regulatory standards.