Geez, mate, give it a rest! Since you readily admit you are not a heating engineer or electrician or anything else vaguely related (nor am I) you have no way of knowing HOW MUCH oil should be in it. ALL oil heaters are partly filled, perhaps for reasons I have theorised before. I also doubt you could buy less than a rather large drum of it, if you could find it. Tell me - any signs of a leak? Do you have an identical heater? If so, weigh both with good scales. That would indicate if oil was low. As I've said before, oil-filled heaters have a very gentle heat, so may not feel as 'warm' as others, still, with a little time they will fill a smaller room with a nice all-over heat. If you could compare identical heaters you might be able to say one was hotter than another.....I suspect it's fine apart from the thermostat, and, chances are, you're on the low setting. I don't think running it without a thermostat is safe, even if you do watch it..... Trust me, I've seen/bought/used a lot of heaters in my day, probably more than most posters here, since I lived in Australia and portable heaters are all 99% of the population use, since few people have central heat. Just chuck it. Get another sort, if you don't like the oil heat type. Personally I like them almost as much as baseboard heaters (and they're easier to cover up accidentally, although I don't know how much risk of fire they pose) - I bought an oil heater for both my daughter's rooms since they were the safest we could find, and they may well have been Delonghis. For us, they worked well but to this day, they still make a hot paint smell when they run. DON'T BOTHER ABOUT THE OIL - YOU CAN'T RESEAL IT, AND YOU HAVE NO IDEA WHETHER MORE OIL WILL HELP OR WILL EXPAND AND CAUSE LEAKAGE ETC.

I should add that the current boiler leaks and is at 75% efficiency...can I wait longer? it's been leaking for a couple years and is rusted outside. We also have forced Hot water baseboards and two zones. Our water heater is electric and up on the third floor . We had an estimate for 5800 for Weil-Mclain? sound reasonable for Boston area? thank you,

We used to have quite a few coal stokers when I was younger. Now we have quite a few customers with rice coal stoves. Here in the Northeast, oil is the cheapest way to go for space heating, domestic hot water production, pool heating and snow-melt systems for the set it and forget it crowd. Most of our fuel customers have oil fired hydronic systems and many have pellet stoves, wood stoves and fireplaces. Many people install gas fired forced air systems in some homes since the initial cost of the system is less due to ultra cheap gas fired equipment, more direct vent options and the fact that the skill level required to install and setup a gas fired forced air system is low enough that almost anyone can install one. This saves a lot of money in professional labor charges and the expense of an oil tank, piping or a chimney, stainless chimney liner, power-venter, oil fired condensing boiler or a direct vent boiler in new construction and and retrofit situations. People that install gas fired forced air work dirt cheap since there's a lot of competition in that market, but skilled hydronics techs and skilled oil service techs command more money so it's reflected in the price.The lightweight gas fired scorched air units are also much easier on the back than hauling large cast iron boilers, heavy duty oil fired forced air furnaces and 500 gallon skid tanks into basements. No need for extra help and you can leave the climbing hand truck at home when you're installing lightweight forced air equipment.

Great information silversilverado, thank you so much! Did you have mold all over or just in particularly damp spots? My red cedar is only on the second floor and is almost completely protected by a big roof overhang (only the north side ever really gets wet with rain), but we are in a region of the Alps that is a bit damp and chilly... I'm wondering if I will have much moisture problem (the 60 year old pine siding we took down was in really great shape). Your advice sounds very reasonable. I just wish I knew if these oil saturators were the same product as an the oil based stain we used in the US, but I don't think so because they are really new and you can only get them clear (they're mixtures of natural oils, like linseed) and since the product itself is the oil, there is no water based equivalent. It's supposed to be the most ecological treatment for wood. I love the idea of trying the product on a sample first. Quite wise. Thanks again!!