It is OK to use any oil that has been certified by the American Petroleum Institute for use in gas engines. If you just bought the car I would recommend 5w30 but 10w30 would be OK. Nissan recommends 5w30. My personal choice of brands is Valvoline. It is just as important to use a good quality filter like the Fram Tough Guard or equivalent.
The 2014 Nissan Xterra has a 5-speed automatic.
The 2008 Nissan Xterra has a 6-speed manual.
The 2003 Nissan Xterra has a 5-speed manual.
The 2005 Nissan Xterra has a 6-speed manual.
The 2002 Nissan Xterra has a 5-speed manual.
The 2006 Nissan Xterra has a 6-speed manual.
The 2001 Nissan Xterra has a 5-speed manual.
The 2010 Nissan Xterra has a 6-speed manual.
The 2013 Nissan Xterra has a 5-speed automatic.
The 2011 Nissan Xterra has a 5-speed automatic.
The 2004 Nissan Xterra has a 5-speed manual.
The 2007 Nissan Xterra has a 6-speed manual.