BigW 8c off a litre starts tomorrow for 7 days. ($35 spend) NO FUEL LIMIT
Often they limit you to 30l or something but can't find anything about that in the catalogue. Direct link has all the information.
Spend $30 in one transaction at Big4 get 4c off voucher then send another $5 at Caltex and you get another 4c off voucher. Easy to do