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Poor Engine Management was the Problem.

This story dates back to 1982.
The switch from a 300hp aeroplane to a 600hp Pratt radial aeroplane came as a bit of a shock considering the fuel consumption rose from 65 lph to 140 lph. To reduce it to what I felt comfortable with I flew at low power settings.
I found the oil consumption remained high: I think it was about 3 gph. It so happened the engine rebuilder, from Los Angeles, was in Australia at the time and the aeroplane sales agent sent him to me in hope that he may address this problem. His name was Vern Truman. It only took him only a few minutes to find the reason for this and it came from my mouth when he asked what power settings I was using.
Solution. Use more power and feed the engine Marvel Mistry Oil because the cylinders had glassed up. Apply this through the manifold pressure gauge line with the engine in idle- that is when a negative pressure existed in the manifold and the oil would be sucked in. Shut the engine down by turning off the ignition. An old engineer from nearby said I should put a teaspoon of Bonn amie in each cylinder. I much preferred Mr Truman’s recommendations.
Mr Truman, an elderly gentleman had worked on radials since he was an apprentice. And he was a gentleman too. Immaculate manners and a pleasant personality. His company traded as Aero Engines and I recall a Pratt representative once said they were one of three companies who could rebuild an engine to as new specs. These engines had long gone out of production and one could only purchase rebuilds.

I never considered fuel burn again. The productivity of this aeroplane increased disproportionately to the extra cost of the fuel. The picture is an Airtractor 301 from the internet. It is the type in this story. The only picture I have of mine is on the wall in my gallery. The engine, likewise from the internet looks likely to be in a Stearman because of the upper wing and undercarriage legs.