See Figures 1, 2, 3 and 4
All Altima and 240SX models are equipped with a catalytic converter, necessitating the use of unleaded gasoline. The use of leaded gasoline will damage the catalytic converter. The engines in these vehicles are designed to use unleaded gasoline with a minimum octane rating of 87, which usually means regular unleaded.
Oil must be selected with regard to the anticipated temperatures during the period before the next oil change. Using the chart, select an oil viscosity for the lowest expected temperature, and you will be assured of easy cold starting and sufficient engine protection. The oil you pour into your engine should have an American Petroleum Institute (API) designation of SG marked on the container. For maximum fuel economy benefits, use an oil with the Roman Numeral II next to the words Energy Conserving in the API Service Symbol.