wd40 is petroleum distilates, and would probably eat your line, if left on there. I've used wd40, to clean off grease, and old glue residue, and it works great for that, but I woudn't put it on line.
100% White Silicone is the same. A 21 oz. can is about $4.00, however I have only found it in aerosol form. (CFC's, Aargh!)Check your local auto supply or wholesale supplier.
Ken, Mil-comm makes a product for reels and line. There web site is mill-comm.com The product TW-25B is what I use on all my auto slides for my firerms, and I haven't found anything better for them. If there fishing product works as well then you should be happy. I know I'm going to try there fishing product.. Hope this helps..