I brake in my engines using 20 % oil and the valve open for 3-4 tanks on the ground with a very rich mixture ......3-4 turns out.
I occasionally check the temperature and don't allow more than 40 deg C during the break in process.
Once I run a tankful through I lean the engine and advance the throttle up but not maximum rpm.I then richen the mixture and keep the process for the next 3 tankful.
When I am happy that the engine responds and transitions I close the valve ....not fully and lean the high speed to about 1 1/2 turns .
At this point I fly the engine and change the fuel to 10% multi viscosity CP and 30 % Nitro.
I always check the engine and regulator temperature after each flight ......I get around 30-40 deg C in the winter and a little higher during hot weather ops.
If I get a high reading I richen the engine ....only one click is enough on the high speed.
I keep the break in valve a little open for at least 40-50 flights .
That also indicates to me it isn't a oil % problem.
Just one of those things 😬