Yes it was stuck valves in this motor.
The oil is what my friend who owned this tried to get things unstuck with ( failed).
Overall this was an easy fix.
I pulled the valves and cleaned it all, then cut the seats and ground the valves to fit better, as it was leaking a lot of compression.
The carb was also corroded badly, so that got a cleaning.
In the end I also changed out the crappy carbs most Wisconsin engines came with one that had better adjustments for air/fuel. This solved the governor speed hunting they tend to do.
This was on a small home built backhoe I had borrowed to do some work here around the house, and I cant stand things working half arsed when I am using them so went a bit farther than just making it run well enough..
It had to run perfect all the time or I would been ticked off, so yeah they got a good deal out of letting me use too.