© 2022, The Minerals, Metals & Materials Society.The requirement for lightweight in automotive and aerospace applications has been the focal point in many studies. Lately, the effect of rare-earth element addition to Al–Si alloys has begun to be investigated in detail. The aim is to establish higher tensile properties with new alloying element additions. In this work, different ratios of Er, Eu, and Dy were added to A356 alloy. T6 heat treatment was carried out with aging temperatures of 145, 160, 180, and 200 C. 10 cylindrical bars were cast for statistical analysis. Weibull distributions were used to check the reproducibility of test results. It was found that Dy addition had made A356 more brittle while Er addition increased elongation at fracture. The toughness and reliability were found to be the highest in 0.1wt% Er-added alloy.