2013 Xterra Owners Manual states:
"In-Cabin Microfilter Standard equipment on
cube, Murano, Altima, Altima Coupe, Armada Platinum, Pathfinder, Frontier LE and Pro-4X Off-Road, Maxima, Titan Crew Cab LE, Quest, Rogue, Sentra, Versa Hatchback and Xterra (except X).
Optional accessory on some models. Replace at specified intervals. When driving for prolonged periods in dusty conditions, replace the filter more frequently.
The In-Cabin Microfilter filters the air you breathe in your vehicle. This system filters both outside and recirculated air used by the air conditioning system in your vehicle. Replacing the Microfilter every year or 15,000 miles is the best way to help prevent road dust, pollen and other air pollutants from entering the interior of your vehicle and the air you breathe. If your vehicle is not equipped with an In-Cabin Microfilter system – see your Nissan dealer about getting one installed – you’ll breathe easier."
In regards to just common Air filters, Nissan offered the following advice:
"How often should I replace my air filter
It's hard to give a specific time or mileage figure because the life of the filter depends on how much crud it ingests. A filter that lasts 20,000 or even 30,000 miles on a vehicle that's driven mostly on expressways may last only a month or two in a rural setting where the vehicle is driven frequently on gravel roads. Changing it annually or every 15,000 miles for preventative maintenance may be a good recommendation for the city driver, but not its country cousin.
Regardless of the mileage or time, a filter should be replaced before it reaches the point where it creates a significant restriction to airflow. But when exactly that point is reached is subject to opinion.
A slightly dirty filter actually cleans more efficiently than a brand new filter. That's because the debris trapped by the filter element helps screen out smaller particles that try to get through. But eventually every filter reaches the point where it causes enough of a pressure drop to restrict airflow. Fuel economy, performance and emissions begin to deteriorate and get progressively worse until the dirty filter is replaced.
Removing the filter and holding it up to a light will show you how dirty it is. If it's really caked with dirt, it obviously needs to be replaced. Trying to shake or blow the dirt out is a waste of time because too much of it will be embedded in the filter fibers.
NOTE: Many filters that appear to be dirty are in fact still good and do not really need to be replaced. So it's up to you. If you think it's dirty, replace it. If you don't think it's dirty enough to need replacing, then don't. In some non-factory air filter appear to be clean, but it's always clean because this filter do not hold the dirt, and all the dirt goes inside the engine.
Nissan How often should I replace my air filter | Nissanhelp.com
However, the argument rests at.. [conservatively] 15,000 mile changes X 6 (12,000 avg miles per year - 6 years (? total changes over life of vehicle) @ $13.99 = $83.94 +tax VS $79.99 +tax X (1) as long as you own your Xterra [washable filter].
Seems a wash.. bragging rights? unlimited expendable funds? Mehhhh, call it what it is.. Who cares if the lil lady [G/F = Wifey] sits with stuffy snot noses in the passenger seat anyway? lolz
in reference to the DEF fluid Its basically refined pig urine, you could almost get away with pissing in it but the truth is in an effort to scrub the air with a $1 for all of the excess dirt licking, tree hugging, faux climate changing underage hippies; places like Kalifornistan have made it so that you have to pay to drive or idle your diesel trucks, pay to add the systems to current trucks in order to stay "Compliant" with Kalifornistan's strict Statutory codes if you want to enter the STATE, and pay for yearly inspections of said systems and all for the sake of dinging drivers, owners, business for something else to further revenue generation.