Does this air fryer need oil？
Instructions recommend a high heat index oil, such as coconut or avocado, to prevent the food from sticking - especially when grilling.
You don’t pour oil into this air fryer. What I typically do is put a few spritzes of a high temp oil like avocado oil spray or Pam Grilling spray onto the basket, put the food down and spritz a few times on the food once in the basket. I’ve made frozen french fries and many other foods without using any oil as well and they come out just fine.
One of my favorite things to air fry is a thin sliced chicken breast coated in fat free honey dijon marinade and then coated with powdered mash potatoes. Makes for a wonderfully crisp outside, the marinade does not burn and the chicken is juicy as can be.
I have the version of this without the thermometer and love it. Use it almost every day.
Great points, @beebles … I should have mentioned that I use a spritzer too. 
I spray both sides of the items I’m grilling and they’ve come out perfect! Like you, I rarely use oil for air frying. I love my Ninja Grill.
As a fair comparison of the deal we are getting here, Groupon has this for $169.99, while Walmart is at $129.99 - and they even use the exact same 3 pictures, so I am guessing those are what is standard supplied by Ninja. In both cases the prices are also for “factory refurbished”. With so many refurbished units available, I wonder if they had some issue creating a large quantity of “infant mortality” - i.e. early failure on this model at one point. Hopefully the refurb units don’t repeat their previous problems. At this price even though I have the larger rectangular 6 qt. version already, I am jumping in for one. The smaller size may make it possible to keep it in the kitchen so I will use it more…