I've used Royal Purple and Mobil 1. I was a big Mobil 1 fan since I used to work for Mobil. I run Mobil 1 in my 97 Eclipse RS but I will be running Royal Purple on the 90 Laser RS. Royal Purple I would say is better then Mobil 1. But I would recommend both, if you can't afford the dollar more for Royal Purple then use Mobil 1.

BTW, Royal Purple and a K&N oil filter make a nice combo IMO.