Should a 1998 seicento have a red key as well as the normal blue ones? or are they just for older fiats?

should have a red key

have a look on the key and if a triangle and number 2 is printed on it then there is no need for a red key

there is a stickey about this in the cinq/sei technical section

i know my '99 did not need a red key

i just read the sticky, and it said for a 1998 it should have one