now that i think about it, and read the manual, i think i may have misunderstood the dude.
His exact words was 'fill it up with super every 3rd or 4th tank'.
where i come from (australia), we use Super to describe leaded petrol.
but after reading the manual today (i just picked up my car today) super is referred to supereuro petrol, which is the equiv of premium unleaded.
which would make sense if i'm using normal unleaded, and filling it up with premium to 'clean out' the fuel system.
and yes, the manual does say that using leaded will indeed kill the o2 sensors and cat.
sorry guys, my misunderstanding