Reminds me of a story about a taxi driver back in the grey motor days (up to EJ) who did a similar thing. Drivers were told to change oil once per week. He worked out it was cheaper to buy a repco short motor and throw it in himself if the grey failed. He worked out that the greys would go 70k+ miles on oil before starting to protest.
From memory he did 60k mile oil changes and replaced short blocks around 110.
