Even though I had no problem burning for DHW all last summer, this spring I was blaming weak boiler draft on the warming outdoor temperatures. Then this morning the boiler draft fan was humming and not starting when I turned it on, which was due to a lot of drag in the fan motor bearing on the hot side of the motor. A couple drops of lube and now the fans starts and I've got plenty of draft again. I keep a can of HHS 2000 around and use it mostly for small electric motors. It wicks in nicely, adheres well, and lasts a long time.