It wasnt really a hoop jump on my first order of Kreen a few months ago, a little white lie is all. The shipping was nearly as much as the product so 1qt plus a free small can of Kroil as ~$35.
I wonder if they are limiting liability this way with the re-seller and also the seller is less liable with the smaller container. I believe they call their stuff for industrial/commercial uses only for consumer liability reasons and could deny any association to this ebayer in Florida. If that person is buying by the gallon its quite a racket for him and Kano knows they aren't loosing any real business.
Frankly i think 8oz might be an adequate dosage, though pricey that way. So my Kreen anecdote...
I was leery so I shot for 3 doses from 1 qt. while also worried about an underdose. 1 sump, 1 gas, and a later sump if I saw a benefit. I put 8-10oz in a 5qt sump, 50 year old Ford V8 w @ 90K miles. It had a "sticky lifter" tap that was there for about 1000 miles I have driven this car. About 2 minutes after putting it into the sump the noise was 90% gone. I won't say 100% because I have excellent hearing:) I went ahead and took a gingerly drive about 20 miles and noticed my oil gauge moving like it never had before which scared me a bit but after draining a refill with a "better" oil i realized the KREEN had cleaned the oil passages or pump or oil sender or whatever magic and the oil gauge needle was moving as it should have been the whole time.
I couldn't really measure the benefit from the gas because it ran well and used good gas regularly, but at least it had a pleasant smell from the tail pipe.
Holding the last dose till closer to next sump drain.