Synthetic and mineral base lubricants have been tested in an overhead camshaft (O.H.C.) Daimler Benz diesel engine.In order to explain the results, the wear of the whole cam lobe (nose and flanks) has been related to the entrainment and sliding velocities, the contact stress and the calculated oil film thickness. A solution to a corrosive wear phenomenon taking place in this Daimler Benz diesel engine has been found.The base oils evaluation has been extended for the overhead valve (O.H.-V.) Volvo B20 and the O.H.C. Lancia Gamma gasoline engines. The Volvo B20 metallurgy has confirmed to be prone to the pitting damage and this engine has been adopted for the evaluation of the antipitting oil properties. The Lancia Gamma engine has been made suitable for the evaluation of the lubricants efficiency against the adhesive wear phenomenon.