This is a medium-viscosity gun oil, for use on fast-moving or reciprocating metal-on-metal components. Roughly the same consistency as baby oil, it will drip and flow freely with gravity, but not as thin as water.
I believe it has tiny particles of Teflon in it, similar to the LT2 grease, but suspended in an oil instead of a grease. Always give it a shake before use - MAKE SURE THE LID IS ON, IT'S NOT A KETCHUP BOTTLE, MY WIFE MADE ME BUY NEW CURTAINS.
In the KC-02 (or G5), this oil has 1 very specific use - to lubricate the bolt sliding around inside the receiver, which is a very fast, reciprocating motion.
You should apply just 2 or 3 drops into the receiver, then spread it all around the inside of the receiver with your finger, being careful to avoid your hop unit as you don't want this to get into your hop rubber and barrel.
Don't apply too much as it will drip down from your receiver into your trigger mech and mix with the grease in your trigger mech, making it thinner and probably ooze out of the gun. Not nice.
You don't need to apply any to the outside of your bolt carrier, just spreading it thinly around the inside walls of your receiver will be enough.
You can also apply 1 drop of this to the long recoil spring guide rod to lubricate the recoil spring. Again, spread it out with your pinky.
You should wipe up any excess from the receiver before re-assembly, so it doesn't get smeared everywhere.
If used carefully, 1 bottle will also last you a very long time as it has limited applications for most guns, but the stuff is so thin, you end up dripping it everywhere, so maybe get 2 bottles if you want to use this on multiple guns.