The effects of engine oil additives on valve train wear

Abstract

Preventing valve train wear in automotive engines i s one of the most importantproperties of anengine oil. However, the influence of engine oil additives on valve train wear has not been suffliently clarifld. In this investigation, the antiwearperformance of additives (such as ashless dispersants, metallic detergents and zinc dithiophosphate -WTP) and the influence of the interaction of the additives were evaluated. Firstly, ashless dispersants (such as succinimides. succinic esters and benzylamine-type additives) did not appear to provide signfxant antiwear protection in valve train wear tests. However, a succinimidecontaining boron demonstrated excellent antiwear performance.Secondly, metallic detergents were considered. An overbased calcium sulphonate and an overbased phenate were found to have good anti-scufmg performance when evaluated in engine tests and in Falex wear tests. However,from the results of four-ball tests, these additives did not appear to have many extreme pressure properties. From surface analyses, it was determined that a calcium carbonatefrlm was formed on the sliding surface of the Falex test piece, and thisfrlmprovidedgood protection against wear.Finally, the interaction of m T P , succinimides and calcium detergents and their influence on valve train wear were studied. The decornosition temperature of ZDTP increased with certain additives, including the succinimide. As a result, scufmg was more prone, at temperatures below those increased temperatures. Also, changes in additive concentration on the sliding surface. due to competitive adsorption, altered the antiwear performance of the oa

Film Forming and Friction Properties of Overbased Calcium Sulphonate Detergents

“…They are also employed in gear and other industrial oils where they act as rust inhibitor and extreme-pressure additives. It has been shown by several authors that these additives can contribute to wear and scuffing control, both when used as additives in simple solution [8][9][10][11][12] and in synergistic combination with more conventional antiwear additives [13][14][15][16].…”

Effects of basestock and additive chemistry on traction testing

“…In these applications the overbased sulfonate is not used as a detergent, but rather as a rust inhibitor and extreme pressure additive [7-l0]. Over the past few decades, the antiwear properties of overbased sulfonates have been explored [11][12][13][14] and these properties were said to be related to the formation of protective films caused by the deposition of inorganic carbonate on the surface of the metal. The effect of this deposited film is analogous to the films deposited by traditional phosphorous and sulfur containing antiwear additives like ZDDP.…”

Thermal degradation behavior of zinc dialkyldithiophosphate in presence of catalyst and detergents in neutral oil

“…As a high polar additive, the detergents may actively compete with the ZDDP for the rubbing surfaces. Rounds [17] and Shirahama [27], have also shown that over-based sulfonates can retard the rate of ZDDP decomposition. Thanks to FeF 3 , which catalyzes ZDDP to decompose at lower temperature in presence of detergents.…”