Gilmour Foam Master II - Settings?

[DaHen]

Does this foam gun sucks out the soap very fast?
I have heard that the container goes empty pretty fast

Yes it does.
If I had a larger vehicle, would have to start with more water.

 

[Curves]

It says in the instructions there are 5 settings. 1,2,4,6,12 oz per gallon. So it make sense to me to put the wash soap un-diluted into the canister and use the setting I want.

Yet, I always read about people diluting the wash soap in the canister. Why do they do this?

I'm using Meguiars Gold Glass.