WD40 and GT85 are both water dispersants. They will dislodge thick muck, grime and dirt - so it's good to use when you've got a lot of built up grease on your chain and gears, or a stuck part that's become rusted. It will get everything looking very shiny. It isn't a lubricant, so you do need to use a chain lube after use and you shouldn't get them near your rims or brakes.