I have a Nissan Sentra 2008 2.0 CVT with 138,000 miles using 5w30 oil and the dealership changed it to 0w20 should I be concerned about it or keep using 0w20 oil in it don’t remember when they changed it about a couple years ago
Follow the recommendation in your owner's manual, or on the engine oil cap if indicated there.
If the dealership put an other than manufacturer recommended oil in your car, take it back and demand they do the job right. Then never go there again, for anything. As @chucktobias pointed out, your owner's manual specifies the correct grade and weight oil for your engine.
Like @chucktobias and @doc said above, check the owners manuals. Also check any technical service bulletins or updated oil guidelines from the manufacturer. I know Toyota updated some of their older cars as compatible with more than one oil viscosity. Not sure about Nissan.
