Calling it a system rather than software is more accurate than it sounds, because the software is the smaller half. A preventive maintenance system is four things that must stay consistent with each other: what you look after, how often each item is due, what a visit consists of, and what was actually done. Sites have all four already, usually in four different places, and the drift between them is the problem software is bought to solve. Naming the parts is how you tell whether a product solves it.
Consistency is the product, not storage
Any of the four parts can be held in a spreadsheet perfectly well. What no spreadsheet does is keep them true to each other: a new asset that quietly has no interval, an interval that never produced a due date, a completed visit filed against nothing. Those inconsistencies are invisible one at a time and are why a plan that looked fine in January is unreliable by June.
The joins to test in a trial
Add an asset with no interval and see whether the system tells you. Complete a visit and check the next due date moved. Change an interval and see what happens to work already scheduled. Delete an asset that has history and see whether the history survives. Four small tests, and they reveal more about a product than any amount of feature comparison.
The part sites forget to specify
What happens at the edges: an asset taken out of service, one replaced by a newer unit, one moved to another area. All three are routine and all three break naive systems, either by losing the history or by leaving a decommissioned asset generating due dates forever. Ask about the retirement path before you buy, because you will use it within the first year.
Questions people ask about preventive maintenance system software
Is a preventive maintenance system the same as a CMMS?
A CMMS is one way to implement it, and a large one. The system is the four parts staying consistent; a CMMS adds work orders, requests and often parts on top of that.
What happens to history when an asset is replaced?
Keep the old asset retired rather than deleted, and start the replacement as a new record. Merging the two loses the ability to say what the old unit did, which is exactly what you will want when justifying the next replacement.
How much setup does a system need before it is useful?
Less than sites expect. The assets that matter most are usually a small fraction of the list, and starting with those beats waiting until every item is entered, which is how implementations stall.