I've posted this before, but here it is again. Changing the oil often does not promote wear. The following is the original study (Ford, ConocoPhillips) where folks have misinterpreted the results,
Valvetrain Friction and Wear Performance with Fresh and Used Low Phosphorous Engine Oils, Arup K. Gangopadhyay (STLE member), R.O. Carter III and Steve Simko, Ford Research and Advanced
Engineering, Dearborn, Mich. and Hong Gao (STLE member), K.K. Bjornen and E.D. Black, ConocoPhillips, Ponca City, Okla.
You can read a generic version here, Valvetrain Friction and Wear Performance with Fresh and Used Low Phosphorous Engine Oils
Synopsis: Used engine oil has carbonaceous elements in it that become a film on high friction areas in engines (ie, valvetrain - flat tappet type). The film provides a barrier, therefore, reduced wear. My guess, is the carbon comes from combustion that under high pressure and temperature (where tappet is in boundary contact), becomes embedded on contact surface and has lubricity properties like graphite, but isn't graphite. If you read the complete paper, you will see that fresh oil does not promote wear.
Valvetrain Friction and Wear Performance with Fresh and Used Low Phosphorous Engine Oils, Arup K. Gangopadhyay (STLE member), R.O. Carter III and Steve Simko, Ford Research and Advanced
Engineering, Dearborn, Mich. and Hong Gao (STLE member), K.K. Bjornen and E.D. Black, ConocoPhillips, Ponca City, Okla.
You can read a generic version here, Valvetrain Friction and Wear Performance with Fresh and Used Low Phosphorous Engine Oils
Synopsis: Used engine oil has carbonaceous elements in it that become a film on high friction areas in engines (ie, valvetrain - flat tappet type). The film provides a barrier, therefore, reduced wear. My guess, is the carbon comes from combustion that under high pressure and temperature (where tappet is in boundary contact), becomes embedded on contact surface and has lubricity properties like graphite, but isn't graphite. If you read the complete paper, you will see that fresh oil does not promote wear.