The influence of Cu and Ni nanoparticle suspensions (2 wt-%) in commercially available engine oil (15W40) has been investigated on friction and wear behaviour of Al2O3-13TiO2 coatings. Lab synthesised nano-Cu and Ni suspensions have been compared with one commercially available nano-Cu suspension. Results show that lab synthesised Cu and Ni increases the oil viscosity by 12 and 20% for Ni and Cu respectively. However, the commercially available nano-Cu has reduced the viscosity by 8%. Lab synthesised Cu and Ni showed slightly reduced friction coefficient with significantly higher mass loss compared to virgin base oil and commercially available nano-Cu. The abrasive nature of these particles may possibly predominate in higher viscosity medium generating steady wear particles from the softer counterpart. Commercially available nano-Cu shows higher and irregular friction profile with mass loss equal to base oil possibly due to reduced viscosity. © 2013 Institute of Materials, Minerals and Mining.