Yeah always have to keep on top of turbos, if equipped. That's one of the few things stopping me from turboing my tractor.
All my engines are naturally aspirated so I haven't worried much about overfueling but whenever it happens it's almost always due to a fault.
I find most naturally aspirated, mechanically injected engines can tolerate a mix of 75% motor oil, 25% diesel without any noticable difference except a change of smell of exhaust, and a little more power. That's for spring-summer-fall.
For winter I have to cut a bit more with gas because the oil gets pretty thick. I use a stick in both cases for viscosity and always mix well before measuring and fueling.
Don't stick it in your tractor if you're worried. It's possible to coke your injectors but as long as you aren't constantly rolling coal it should be fine.
Good luck, I've had great success.