I measured about 82.5 percent when I first ran the DF520 with oil. What is typical efficiency expected with the DF520 burning oil? I have to switch to oil when I travel, and interested in knowing what people have measured with the DF520. I brush off the ashes in the boiler before I switch. Is there anything else I should do to optimize the oil burner combustion efficiency when I have to run on oil? Also, I noticed I can not reduce the smoke to zero when running on oil. Best I have been able to achieve is 1 on the smoke test. Is this due to the coal in the pot? Should I cover the pot with a blank of kaowool?