Well.....all I know is....
We get pissed when the customers who let us do it for awhile and then decide to let somebody down the street do it because it's cheaper. AND, the customer ends up bringing it BACK to us so that we can solve their problems regarding oil/filter changes. When they should have brought it to us all along.
They ALWAYS come back.....whether it is the customer or the "other guys" trying to fix a problem and don't know how.
I've seen it all....Circuit City, Best Buy, other German auto shops....come to us to solve their problems.