After looking around Royal Purple is now sold in Bulgaria, along with Castrol. I'd use a 10w-40 or 5w-40, but don't know if the EJ20 is really hard on oil. I've had good results with Royal purple in my RX-7.
I run Castrol Edge 0w40 in my 2005, and it loves it. I've run Rotella 5w40 and Pennzoil Platinum 5w40 as well. I used to run 5w30's in it, but the 40 weight oils seem to quiet the engine noise a little.