Many people spray WD-40 on their sliding screen and door tracts. WD-40 is an excellent product, but using it as a lubricant is the wrong application. WD-40 is a rust preventive. When used on door tracts it attracts dirt and dust which results in a gummy substance building up. This gummy substance binds up the smooth operation of the doors. The proper product to use is silicone spray. Use of this product will keep your doors sliding like new.