I got my first hand gun in Nov of 2010 -- a Glock 19. Like you, I thought the manual was a bit vague. There are many YouTube videos on how to clean/lubricate these -- and everybody does it a little (sometimes a lot) differently with different products.
So I called Glock directly and here's what I was told about lubricating the gun....(assuming you've already cleaned it)
- The guy I spoke with recommended using Breakfree CLP
- Put 1 drop on either side of the frame on the rails, do the same on the slide
- Put a drop on the barrel and spread it around
- Assemble the gun and rack the slide several times to spread the oil (that's 5 drops total)
You can wipe the outside of the slide with a drop if you want to clean it up / wipe it down.
They require very little lubrication. On some of these YouTube videos, you'll see folks put oil all over these guns and it's just not necessary. Long-term, the excess oil can hold dirt and cause problems.
IMO, these are very easy guns to field strip and clean. If it takes you more than 5 minutes to clean the gun -- then you're probably overdoing it.