Recently, research on cost-effective nanoparticles for improved and enhanced oil recovery has attracted increasing attention. Most of the existing research activities on the effects of nanofluids were focused on the alteration of wettability and the reduction of interfacial tension. However, in those studies, the nanoparticle solutions were presumably composed of not only bare nanoparticles but also with stabilizers or surfactants. It becomes ambiguous which components in the nanoparticle solutions played a role. In this work, we used a waxy crude oil and aluminosilicate nanoparticle to resolve the ambiguity. The objective of this work is to investigate the oil displacement mechanism by nanofluid through the measurements of the wettability index and interfacial tension as well as through core-flooding experiments. These experimental results showed that aluminosilicate nanoparticles could alter the rock surface wettability from water-wet to stronger water-wet and decrease the interfacial tension between oil and injection fluid. On the basis of the results, the effects of aluminosilicate injection on the improvement of oil recovery were confirmed, which suggests that aluminosilicate nanoparticles can increase the recovery of paraffinic oil with an asphaltene content of 25% in a water-wet reservoir.