Stella has been watching heating oil prices for weeks—she found a site with a price-vs-time graph and added it to her browser bookmarks, and would refer to it frequently as the prices dropped, considering when to buy more oil before the price rose again.
We finally ordered some oil towards the end of the year, as the price approached €0.50/l and I thought it wasn't likely to fall much more, and also before some tax or other would have made oil more expensive as of 2009. (Of course, the price did fall a bit in the days following our order—but not all that much; from €0.54 to €0.51 or something like that.)
Figuring out how much to order was a bit more difficult, since the gauge on our oil tank in the cellar is calibrated in centimetres rather than litres. But since she knew how much the tank was supposed to hold and what the largest number on the gauge was, Stella had a ballpark idea of the cm/l ratio, and figured that our tank could hold another 2200 l.
Since I wasn't sure how reliable that conversion rate was, I recommended that we order a bit less, so we placed our order for 2000 l.
We had asked for them to deliver the oil in W1 (29 Dec–2 Jan); shortly after we placed the order, we got a phone call from the company that the web site had forwarded our order to asking whether W2 would be fine, too, since they had so many orders that W1 was already fully booked. That was perfectly fine with us, since our tank is still about half full; we just wanted to lock in the price.
Last week, we got a phone call telling us the oil would be delivered today; when I asked for a window, I got told between 08:00–10:00.
This morning, the tank lorry pulled up outside our house at 08:15, just as Amy and I were about to leave, and I decided to hang around and watch the chap fill our tank. (Stella had previously sawn through the lock on the cap on top of the pipe... we couldn't find a key for it among the keys we had been given when we bought the house.)
So he hooked up some kind of sensor first (that would figure out when the tank was close to full) and then the hose, then asked whether he should just fill up the tank (rather than deliver a specific amount of oil), so we said yes.
We had to turn off our furnace, which Stella couldn't figure out how to do quickly, so the chap simply flicked the "emergency off" switch. That worked :)
After about a quarter of an hour, the pump switched itself off as the sensor detected that the tank was full—and the meter read: tada, 2199 l! So Stella was really close with her figure of 2200 l :D
The chap said we should leave the furnace off for at least another hour (perhaps to let thing settle? no idea); later, I got a phone call from Stella saying that once she switched the "emergency off" switch back on, the furnace seems to have started up fine by itself and was chugging along. So that's good.
Now we have, by Stella's calculations, enough oil for two to three winters, depending on our heating habits.
(She also asked the chap how much their minimum delivery was, and he said, about 300 l. Depending on thing such as the length of the hose they need, but for our house, 300 l would be what he'd be prepared to come for. So depending on what the oil price does, we may top the tank off before it gets empty.)