Ok. I know very little on this topic. I was assuming my roughly 37 year old boiler was a massive problem. However, it has been very well-maintained, as far as I've gathered. I'm still near the upper end of that 30-40 year time frame, but I figured it probably should have been replaced 10-15 years ago. Must be the curse of modern living - I just didn't think oil boilers were built to last that long. I appreciate the insight.