..and teh answer is ..buy now.
I got an online quote of 25.2p a liter from
Oil prices are hovering around $50 a barrel, so I took out some call options on $50 a barrel, and will be in the money at $51 a barrel. At $52 a barrel I will make about a third of the oil bill back, and if they rise any higher it will pay for the christmas tank :-)
So buy now, armed with a good online quote. Stocks are high as its after the winter shortage, and before the summer petrol burn. Apparently.