I have an old 2003 Toyota Corolla, had just under half a tank in it. Put some fuel preservative in and topped the rest of the tank with 98 octane fuel at about $2.50 a litre, cost $60. Don't do many miles in it as it is a car I hang onto in case the company decides to stop allowing personal use of the company car. We are in negotiations at the moment and the 2nd hand car market has gone up in value majorly. Wise to hang onto it. The tank will last a good year or 2, hence the fuel preservative.