Pour the oil on a baking tray (or oven-proof casserole dish) and spread over the surface. Prick the sausages with a fork several times and place them into the baking tray. Place into a preheated low oven at Mk 3 - 325ºF - 170ºC for about 20 - 25 minutes turning from time-to-time so that they brown all over.