To Seal or not to Seal

[pleaseadvise]

My 30yr old Weil McClain boiler now has two small leak but am not ready to replace without some research. The oil company said they can put in a sealer that may last for a while but a plumber told me that it leaves a residue in the pipes and can cause problems with the coil when a new system is installed. Opinions?

[Tom Sawyer]

sealer is almost always a waste of time and money. 30 years old, time for it to go. Look into a Buderus