WD-40 doesn't lube your chain.
It cleans it well, I use it for that too, but it isn't a proper lube. I clean my chain, then I lube it.
Home depot sells DuPont multi-purpose lithium lube. That stuff self cleans and lubes in one shot.

The gates also have the new titanium wheels. I had a gate that the wheels had lube fittings and had to be lubed with a lube gun.

We had a golf cart that had 12 lube fittings, the only problem is the lube gun would bleed lube in the heat when not used. even the box I kept it in would become saturated with lube.

A gate company told me not to over lube the gate chain because the fine dust is what eats away at the plastic sprockets.