Gaming the System... Or is it stealing?

I want your opinion if this scenario is stealing or completely ethical.

Friend of mine is trying to save money without lowering his quality of life. He likes coffee with liquid creamer. He pays a few dollars for liquid creamer at the grocery store where he buys his coffee.

But he’s decided not to buy the creamer from the grocery store any longer because he’s found a better deal. He recently bought a cup of coffee at a service station, where he found the creamer to be free (with coffee)... but was appalled by the $1.70 of a 24oz cup.

The gas station creamer is dispensed from a large container with spout. So he’s decided to fill a 24oz cup completely with the creamer (and use it for his home brewed coffee)... but at the register, the clerk charges the normal $1.70 as if it were just a coffee.

He still makes his coffee at home, but gets 24oz of flavored creamer for $1.70. He says that is about ¼th the cost of buying it at a grocery store. I don’t know how much creamer cost, so I can’t verify the price.
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So, is this ethical? It seems perfectly legal, but somehow to be gaming the system. I’m not sure if there is a limit put upon how much creamer someone could add to their service station coffee cup.

My friend isn’t worried about the ethics of it. He justifies it by claiming that service station sells over two thousand cups of coffee per day… at $1.70 each.

What do you think?