I don't use rail lube. PTFE Teflon tape is much cleaner. You will have to search on eBay for your own country but here's a link for what to look for. On eBay just type in teflon adhesive and go with the appropriate width for your rails. Make sure to clean the gunk off with a degreaser before you install.
http://www.ebay.com/itm/INU-Nonstick...item1e7c7f232f