Hi Fabian.
As Brian already mentioned, you might need to use javascript.
I'm not aware that you have something like "system_time" avaliable in a pdm_if context
and you should use $args.date_attribute_INT_DATE
so, something like
if("$args.warranty_end_INT_DATE" != "" && $args.warranty_end_INT_DATE < (new Date).getTime()/1000 ) {
alert("Out of Warranty");
}
might work.
Be aware that ...INT_DATE will return epoch time stamp in seconds (UTC) while (new Date).getTime return epoch milliseconds in local browser time!
Regards
............Michael