I'd keep an eye on your oil consumption
If the paper fibers decided to stick to the cylinder walls, the rings could pick them up. Over time they will turn to carbon and possibly reduce compression
or increase oil consumption
If the compression
rings get gummed up, your engine will be difficult to start. If it is the oil rings, your oil consumption will go up.
I agree with the previous posters about the desirability of adding a filter, but most diesels have a screen
across the intake to stop gaskets and towels. It sounds like your engine doesn't have one.
On semi trucks, where the intake is pretty large, sucking towels and gaskets into the intake isn't uncommon. The intake airfilter, which looks like a shopvac filter is supplied with a new gaskets which are shipped inside the pleated cylinder. I've had mechanics throw the filter on without removing the gasket
. The truck runs fine until the gasket
makes its way down to the screen wher it starts cutting off airflow. This makes the engine put out black smoke like you just blew it up. It is an attention grabber the first time.... Inconvenient, but the fix is easy.... just remove the gasket from the screen. I never had one pass through the engine, though.