you should use 10W-30 of any reputable brand of oil. With a car that old, I would also add an oil additive like Slick 50 or similar for older engines. They cost a lot, but definitely keep your engine running smoothly.
synthetic valvoline
It is important to use the right type of motor oil in a car to keep the car performing well. A 1999 Nissan Sentra GXE uses 5w-30 or 10w-30 engine oil.
The oil you should use depends on the climate you live in. In more mild climates (such as Southern California) the proper viscosity is either 5W30, or just plain old 30W. As far as brand is concerned, I prefer Valvoline conventional, or Royal Purple full-synthetic.
The 2006 Nissan Sentra runs on regular unleaded.
The 2010 Nissan Sentra runs on regular unleaded.
The 2005 Nissan Sentra runs on regular unleaded.
The 2008 Nissan Sentra runs on regular unleaded.
The 2003 Nissan Sentra runs on regular unleaded.
The 2012 Nissan Sentra runs on regular unleaded.
The 2004 Nissan Sentra runs on regular unleaded.
The 2014 Nissan Sentra runs on regular unleaded.
The 2009 Nissan Sentra runs on regular unleaded.