Thermal decomposition of zinc dialkyldithiophosphate (ZDDP) is examined in presence of a noble catalyst iron fluoride (FeF3), using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The influence of heating rate, isothermal holding period and catalyst concentration was verified. The role of FeF3 on ZDDP decomposition mechanism was analyzed using 31P-NMR. This study also focused on the effect of FeF3 on ZDDP decomposition in combination with detergents (Ca-sulfonate, Mg-sulfonate and Cophenates). The decomposition temperature of ZDDP is reduced significantly in presence of FeF3. Thanks to FeF3, the ZDDP decomposition temperature is lower even in the presence of the detergents, while the detergents greatly retard the ZDDP decomposition. The 31P-NMR studies confirmed a faster decomposition and a different decomposition mechanism of ZDDP in presence of FeF3