X2's can be found on the shelves at Wallyworld in hermetically sealed "Pringles" cans. But, Wix/NAPA Gold oil filters are the good stuff too. I used Wix up until I got the engine flushed out and clean. Spun on an X2 and filled her up with magic green oil. She'll go as long as April of '06 or so and I did this last month.
