Not every job starts with a breakdown. Some start with the decision to prevent one.
My 1989 SEAT Ibiza had no cooling problems. Even so, as part of the restoration I decided to flush the water circuit and the heating circuit.
I didn't find anything worrying. Nor was it an especially complicated job: a few old gaskets and a task that asked for time, even if the result wasn't very visible.
I cleaned both circuits myself. As part of the car's general maintenance, I also changed all the fluids and the fuel filter.
This part of the project has taught me to value the less showy jobs. After working on the engine, I also wanted to look after the circuits that support it, even though they had given no sign of failing.
That said, doing this work doesn't let me treat reliability as proven. The car starts, but I can't drive it yet and I haven't been able to judge how the whole assembly behaves on the road. On top of that, the wiring still needs to be checked and tidied.
For now, I have part of the preventive maintenance done. The checks will come later.
This project is also teaching me to tell the difference between a finished job and a verified result. To me, having judgement means being able to explain both with the same honesty.