Welcome to FT, xelaw! ^^

I assume you are talking about upgrades on EWR-TLV. If this is the case, all but the two most expensive economy fare classes will require a co-pay in addition to the miles.

Check out the Interactive Reward Chart and click on the tab that says "Upgrade Rewards" for co-pay details. You will notice that the lower fare classes (WESTNL) have a higher co-pay than the higher fare classes (M, H, K.)

You can also check out the FAQ here: http://www.flyertalk.com/forum/7374772-post32.html

Hope this helps!