Ashless Anti-Wear Additives

Ash-forming metals, such as zinc, calcium, or magnesium, can be problematic in some applications because they cause deposits, for example. This often results in increased maintenance frequency, reduced efficiency due to clogging, and shorter oil change intervals. In addition, the degradation products of ash-containing anti-wear additives (AW additives) promote the oxidative aging of the lubricant and thus reduce its service life. For this reason, ash-free AW additives are preferred, especially in turbine and compressor oils and in certain hydraulic systems (e.g., HFC, HFDR).
Ash-free wear protection additives are not only used in high-performance applications, but also when special requirements are placed on the additives—for example, with regard to color, labeling, approval for environmental labels (e.g., LuSC list, RAL UZ 178), or suitability for contact with food.
Many ashless AW additives are multifunctional and, in addition to wear protection, also improve corrosion protection, EP performance, friction coefficients, and the oxidative stability of the lubricant. For this reason, combining zinc dialkyldithiophosphates (ZDDP) with ashless AW additives can also be beneficial: this allows the advantages of both systems to be exploited while reducing the ash content.