The chain on the front gate’s drivetrain needs to be greased every 6 months. We use marine grease for the job (shown below).
 
You’ll want to wear rubber gloves while greasing the chain to avoid getting completely messy. Greasing the chain is easy enough, just dip your fingers into the marine grease and then wipe the grease on to the chain. Aim to apply grease on the center of the chain links. Wipe off any excess as you go.
It’s straightforward to grease most of the chain while the gate is closed. The one exception is the part of the chain that is on the drivetrain while the gate closed. To grease that part you’ll need to climb into the bushes behind the drivetrain and have a friend open the gate. When the gate is open you’ll have just enough time to grease the chain before it closes again. Be careful not to get hit by the gate as it opens.