Most normal failure mode is a cracked piston, ring (s) or ring land. Usually applies to smaller diesel engines, kubota, yanmar, shibora, Perkins, Mitsubishi, cat, etc all suffer the same fate. Larger engines are much more forgiving, but not invincible to breaking. Steel pistons/ crowns seem much less affected. Most mfg of diesel engines these days do not advocate for starting fluid to be used. There are a few that still offer either start systems, but the days of manually unloading a can are over.(expect for the determined idiot.) Modern diesels just don't need it thanks to electronic fuel management, multi injection events and the ability to control timing basically infinity to crank/cam rotation. Last D-11R I worked on still had a either start system, but wasn't needed even in freezing temps. Besides that, the system was made just about idiot proof. Metered amount of either and would only inject after you started to crank the engine.