Surgery - Colorectal. In brief: Yes, most docs can. Most hemorrhoids should first be treated by conservative measures, such as bulking the stools, education to avoid bad habits like straining, sitting for long periods of time, etc.
Either system will have a burner. 23 years may very well be beyond the typical life expectancy of a oil burner, but a furnace or boiler should last considerably longer than 23 years. The boiler of my house here in MA is 58 years old and still works fine. I am starting to consider replacements, however.
I just had a leaking power vent gas water heater replaced after a month short of 10 years. It's a rental. I asked the tech if they should last longer than that and he said 6-10 years is normal in a hard water area like mine. installed a 30 gallon fast recovery gas water heater with a standing pilot 30 yrs ago, my son lives there now and its still operating. This is a Sears/Kenmore model. I also replaced a boiler at the same time and that needed new burners because it did not have a standing pilot.