<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Swanhunter:
Useful warning about miles expiring after 36 months Peter - I'll just have to spend them.</font>
I'm not sure if you got peter42's answer correctly: the miles don't expire if you have status (FTL, SEN) or an LH VISA card. Otherwise the miles expire after 36months.
As you want to reach SEN level, you don't have to care about the 36months rule.