Synthetic oil is not required to ensure that your Nissan Altima meets Nissan’s specifications. Only 5W-30 weight oil with an API classification of SN is required. This is printed on each quart and gallon container, and it satisfies the standards indicated on pages 9-5 and 9-6 of the Altima owner’s manual.
Therefore, there is no need to spend more money on synthetic oil for your Altima; the 5W-30 weight oil with the SN label should enough! And if you are uncertain about the type of oil to use, examine your owner’s manual or contact your local Nissan shop for guidance.