An interesting experience I had with oil on the lower tube sheet: Sue Davis of the Stanley museum put up their 1916 Stanley touring up for the winter. The 1916 Stanley was a condensing car with a good tight boiler. Sue drained the boiler of water, then topped the boiler off with kerosene. The following summer, after draining off the kerosene and refilling the boiler with water, I fired it up the Stanley her. The Stanley fired up normally and everything went along fine until the burner cycled off. That is when the lower tube sheet let lose with a rain storm of leaking fire tubes. It would hold steam pressure only up to about 250 pounds and leak everything above that. With leaking fire tubes, Sue drove the car about a mile, down to her home and put it into storage for a couple of months. Later when she refired it, She said that the boiler worked perfectly and it never leaked at all. Go figure?? My guess is that kerosene and oil got between the fire tubes and the lower tube sheet and with the oil being present water was able to pass. After a couple of months of sitting with just water in the boiler, the oil degraded to the point that the fire tubes were no longer leaking. She said that the boiler operated like new again with no water leaks. The moral to this is: oil between the fire tubes and tube sheet cannot be a good thing. Any theories of what went on here would be appreciated?
It is always said that Stanley's switched to the welded tube boilere because they found the returning oil from the condenser caused tube leakage from the swaged copper tubes. However how do we square this with the recommended method of cleaning boilers by adding Kerosene to a hot but empty boiler and then blowing it down. Perhaps that was only for condensing cars with steel welded tubes.
Years ago a friend used kerosene as a coolant in his 1933 Phantom 11 Rolls Royce to discourage the corrosion to which the aluminium head is prone. it worked perfectly although all gaskets in the water connections had to be good. It smelt a bit (!) but ran cool enough. Ran like that for several years and the kerosene made the brass tubes in the radiator come up bright and clean, shifting all deposited minerals and crud.
Perhaps the difference between the Stanley recommendations and Sue Davis' experience is that a quick flush with hot kerosene is ok to clean the boiler, whereas leaving it full of oily kerosene over the winter gives the mixture time to seep into the tube end joint, causing leaks.