For those of you switching to synthetics, what is the viscosity you have used? I want to switch to Mobil 1, and it seems that either the 5W-30 or 15W-50 is recommended (according to the Mobil 1 website). Thoughts or opinions?

 

I've always used 5W-30, as Nissan recommends, epecially since it gets cold in the winter here. When its cold, 5W-30 flows easier and minimizes wear. I've never used 15W-50, maybe some of the racers have, since its a warm weather weight, I believe.?

 

5W-30 Valvoline and Mobil 1 works for me...