For as well as WD40 appears to work, keep in mind that it's primary purpose is to displace water, hence the WD. Sure it'll help prevent rust, but the hilift could use better lubrication. There are a lot of things out there that will lubricate better, consider a can of 3in1 oil just for the hilift. Can of silicone grease spray probably wouldn't be too bad either.
Whichever you use, the lubricant will attract dust, so the more protected the storage the better.