Your doctor looks at bloodwork to see what’s happening inside your body, right? It makes sense, analyzing your blood can give an indication of problems that you can’t see.
Oil analysis is no different from blood work. Fuel dilution in motor oil? Maybe you have an injector problem. Coolant dilution? Maybe you have a bad liner. Excessive wear metals? Copper? Iron? Are the additive properties of your motor oil depleted? All of these things are indicators of something that’s happening. Something that could cost a lot to fix if not addressed immediately. Equipment is expensive to buy, operate and repair, so spending a few extra dollars on simple to use and very informative oil sampling is a very good idea.
Some people view oil analysis as “looking for trouble.” Consider that maybe everything is fine with the oil and you should consider extending oil drains. Avoiding oil analysis because you may find something wrong is bad idea. Every time, all day long.
Any way you look at it, oil analysis programs are very cheap insurance for very expensive equipment.