Motor oil advice - Nissan primera P12 '03

[winkeyf]

Hi everyone,

I will be servicing my car this week, and I wanted to know which motor oil I should use.
Nissan recommends a 10W-40 semi synthetic with a rating of SJ. a friend with an older car ('98 Seat Ibiza) told me he's using this oil and is happy with it. it's a grayish oil premixed with MOS2 additive for better cold-start lubrication.

Will this oil be a good choice, or should I use another (SL rated? maybe a full synthetic instead of a semi?)

more details about the car:
engine: QR20DE 2.0L petrol
mileage: 81000 Km

thank you...

P.S.
I tried to find some material on API SJ vs SL with very little success... is SL "better" then SJ, or are they just different in such way that SJ contains additives that are suitable for one engine, while SL contains additives that are suitable for another engine?