“Any color, as long as it’s black.” Henry Ford’s famous words referred to the rationalization of early car production. Black paint quite simply dried the fastest. A century later, rationalization, this time at oil refineries worldwide, could again open the door for black – Nynas’ highly viscous base oil BBT 28.
In a comparative study, Nynas prepared several lithium- based greases based on base oil blends with different viscosities (235, 370 and 505 mm2/s) where the starting point was a solvent neutral (SN 500). Since the viscosity of SN 500 was around 90 mm2/s, various amounts of bright stock or BBT 28 were required in order to reach the final viscosities, before a battery of tests were conducted. Overall, BBT 28-based greases showcased some interesting behaviors, such as lower thickener content, good shear stability, good low-temperature flowability and superior water spray-off.
How would the greases behave in cold weather? Tests such as flow pressure or rheological measurements such as a temperature sweep program could give valuable information regarding the flowability of lubricating greases. Such test programs were applied to the greases down to –25 °C. The outcome revealed that paraffinic-based greases had a significantly higher elastic modulus at –25 °C than the paraffinic/naphthenic-based greases, due to the further wax crystallization of the bright stock. Notably, further study found that BBT 28 had an excellent thickening effect; in order to obtain a shear stable NLGI grade 2, less than 4 (wt%) of the lithium-based thickener was needed.
Nynas™ BBT 28
■ Significant reduction in thickener content
■ Good shear stability
■ Very good water spray-off, probably due to BBT 28’s higher adhesivity
■ Similar wear scar as the bright stock-based greases
■ Comes in the never-out-of-fashion colour black