On Dec 3, 11:49*pm, wrote:
I purchased a house built in 1951 about 7 years ago......It still has
original boiler which is still working well. *The only thing I have done is
fix a couple of leaks. *I did not add a rust inhibitor, refilled with water
only. *What should I do in terms of maintenance?

Get rid of it.
A new one will pay for itself in a few years in reduced fuel bills.