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Tatulover1 I don't think so.
What I was referring to is overcharging for everything, but especially rounding up the oil used to a full quart. If your oil change takes 4.4 qt, they sell you 5 qt.
If the next person's change takes 3.8 qt, they sell him 4 qt.
So they sold 9 qt but used 8.2 qt; they oversell by rounding up.
Or to think of it another way, they sold you not just the 4.4 qt you needed, but the 0.6 qt you didn't; that might be used on the next person--and RESOLD to them!