RE: 120hp Lehman lube
This result simply shows that engines DO BETTER , being run.
Every oil is about 20% addatives , that actually do work .
A nice long run like the ditch will make any engine happier, and most ant detergent oil is going to help, if changed with a new filter on time.
Most engines do run better with the lightest oil that will not depart past leaks or the rings.
So a switch to multigrade , sometimes is a help.
Personally I am a single weight fan .I care about how long the engine goes before overhaul , less about oil consumption.
Oil is cheap, engines , esp non industrial that need to be removed for overhaul , are a drag to refresh.