A series of tests have been conducted to study the effect of titanium and strontium on the fluidity of liquid A319 and A356 aluminum alloys. The increase of titanium enhances the fluidity of the A319 liquid alloy due to its high potential to refine the grain size because the presence of particles increases the solid nucleation rate. For the alloy A356, the fluidity index increases with the increase of strontium, eliminating the occurrence of cold joint defects. Therefore, it is concluded that titanium and strontium enhance the fluidity of these liquid aluminum alloys. It is expected that cast defects will be reduced. Care has to be taken, as a very fluid metal can also be harmful.