I have a rainwater tank with a pump. The pump wasn't serviced since we bought the house. What service should be done for the pump? The label shows to put some kind of oil.
Thanks in advance.
That's to prime the pump if it runs out of water. It's a centrifugal pump, nothing needs doing to it unless it starts to leak or the bearings get noisy.
Agreed with Brendan - nothing to do on these types of pumps apart from just giving it a quick brush off and light clean occasionally (external body). A proper enclosure (you can buy them for pumps) will assist longevity especially if its in sun.
As Brendan said, eventually it will leak whilst its in operation and the bearings will get noisy. You can keep using it when it's leaking - I only removed mine last year (11 years old) as it was leaking mains water (it had a main to rains auto switch system).
Just don't touch it until it dies. Simples