I have a 2013 Nissan Altima with a 2.5l does it require synthetic or conventional oil?

The answer to your question depends on the owner's manual for your 2013 Nissan Altima. You should always refer to the owner's manual for specific oil requirements and recommendations. However, most newer vehicles with turbocharged engines generally require synthetic oil, while most non-turbocharged engines can use conventional oil. So, if your 2013 Nissan Altima has a turbocharged engine, it is likely that you will need to use synthetic oil. Hope this helps!