Controlling Lubricant Acidity With an Oil Conditioning Filter

Abstract

In modern diesel engines, acidity generally determines the lubricant drain interval. To control acidity, lubricant suppliers incorporate detergent additives to neutralize acids that accumulate in the oil via exhaust blow-by and base-stock oxidation. However, formulations that meet the most recent diesel lubricant classification specifications typically contain lower levels of detergent since this additive contributes to ash that fouls emissions aftertreatment systems. This study explores a novel approach to lubricant acid control as a potential means to reduce additive requirements or increase oil drain interval. The authors investigate the performance of an innovative oil filter that releases no additives into the lubricant, yet enhances the acid control function typically performed by detergent and dispersant additives. The filter chemically conditions the crankcase oil during engine operation by sequestering acidic compounds derived from engine combustion and lubricant degradation. Long duration heavy-duty diesel engine tests show that the filter reduces both the rate of Total Base Number (TBN) decline and the rate of Total Acid Number (TAN) increase by a factor of two. Analysis by Fourier transform infra-red (FTIR) spectroscopy also indicates that lubricant oxidation may be lowered. In addition, these results suggest a reduction in engine wear. These results imply that lower lubricant additive levels in combination with this novel oil filter may be used to reduce ash accumulation in diesel aftertreatment systems, while maintaining adequate engine protection. The results also indicate that the engine operator may use this oil filter with a state-of-the art lubricant to lengthen oil change intervals.

Extension of lubricant drain interval by modified pure biomass oil filter

“…The authors proposed that the acid impurities and dispersant in oil would occur neutralization interaction at the zone of a piston ring in the engine. In this region, the lubricant is exposed to acidic combustion gases and high temperatures (greater than 250°C), which result in severe oxidation 13 . The formulated lubricant itself has the ability to adjust the acid formed in the oil by neutralization to give rise to form neutral acid‐dispersant complexes.…”

“…Normally, the most widely used material for filtering oil is synthetic fiber paper, which removes particles in lubricating oil through the physical action of adsorption or filtration, 11 but it cannot effectively control the increase of acidity and maintain the alkaline reserve. Several works focus on investigating the methods and technologies to slow down the deterioration of lubricating oil by effective additive packages 12 and oil filters 13 . This work believes that biomass materials may be a potential substitute for traditional filter paper (FP).…”

Limitary State of Heavy-Duty Engine Oils and Their Evaluation According to the Change of Tribological Properties during Operation

“…Therefore, it is very important to pay attention to oil acidity behavior during operation if oil producers want to assure the long-term efficient operation of their engine oils. The monitoring of acidity indicators and its control by neutralizing additives and oil filtering could be applied for this purpose [8,[10][11][12][13]30].…”