Your na will be fine with pretty much all oils. Just use what the manual says to use.

For the record i use and have used 10w40 Nulon Fully Synth for years now in my GT and WRX.

As Brunei has avg annual temp of 35c, I just changed mine with a L.Moly fully synth 5w-40 . . .methink the EJ20 is loving it . . .

Just swapped to Total Quartz Racing 9000 5w50 and got rid of Mobil Super S 10w40 ....engine is running so much better. Thanks Doug!

Helps when you actually have oil in your engine to begin with dude haha.