Engine damage caused by oil bath air cleaners
Oil bath air filters were replaced by more efficient paper-type filters more than 50 years ago in the majority of the vehicles and equipment. An oil bath air filter can filter fairly well in a stable motor, but not where the oil is able to move. They also require constant cleaning and monitoring of the oil level.
Here we can see the history of three oil changes in a small IVECO truck equipped with an oil bath air cleaner. You can see that each oil sample had between 48 ppm and 97 ppm of dirt in it, resulting in very high wear rates. A paper-type filter element would only have 5 to 10 ppm of dirt (silicon).
Note: This truck used a very high quality Synthetic oil.