Toyota Repair: 1994 toyota 4x4, radiator cores, gm dealership

Question
I was told that I have possibly a small crack in the head of my toyota pickup.  The man that I spoke with told me to go to a GM dealership and ask for radiator pills and to crush them up and put them in my radiator and run the vehicle for a hour.  Have you heard of such a thing? If so, Does it work? If not, What do you recommend? There is a just a small amount of water mixing with the oil on my cap and not on my dipstick.  Look forward to hearing from you.  Thank you.

Answer
First of all,those "pills" or other additives seldom seal a cracked head, may be a leaking headgasket but temporarely at best, not only that but the stuff can clog radiator cores creating more problems, my advice is to not use them but you can try if you wish.
Most of the time it's the headgaskets that leak, heads seldom crack on the V-6 but they do sometimes on the 4 cylinder. How does he know it's a crack rather than just a headgasket without removing the cylinder head?
What I recommend is removing the cylinder head(s) for inspection of the headgasket, V-6 engines are very prone to headgasket failures, on the 4 cylinder the head should be tested for cracks at a reliable machine shop.