Regarding the SM: Before starting engine, put vehicle horizontally and check the engine oil level. If engine is already started, stop it and allow 10 minutes before checking (it is better to check engine oil level when the engine is warm so check it 10 min. after stopped).Regarding the grade 5W30 is recommended by Nissan.
I use Mobil 1 or Motul but all good brand ok, I hope this help