If you co-ordinate your oil delivery with one or more of your neigbours, you get a discount as you save on delivery costs.
In Kanton Aargau, I use
http://www.heizoel-fredy.ch/ - the son of the owner (Robert) speaks and writes English and is very helpful.
I still cannot get over the concept of having to try and judge when to buy my oil and how much to order. The prices fluxuate so much. 6 months ago I paid 127 chf per 100 litres, today it is about 73 francs. For a 4000 L tank, this is a hell of a price difference.