Can you sell it?

To run a successful auto repair business, being good at sales is just as important as any other skill in the shop. Tell me how you would answer this customer:

When they first came out, I had a chance to try a vacuum tool that’s used for leak-checking and filling a cooling system. The brand name was Airlift, and I think there are some other brands now, but these days the tool is generically called an ‘airlifter.’ I remember being impressed at how fast and easy it was to fill a cooling system that I’d had trouble bleeding in the past (VW Corrado with the PG engine). Later I read that some people won’t to use the tool on certain GM engines that suffer a high rate of intake manifold gasket failures. People have also worried about collapsing a radiator or breaking plastic tank or sucking in a tank gasket.

A common line of thought is 'If it’s that close to failure, better it should happen in my bay rather than after I’ve returned the car to the customer.'

True enough, but someone has to convince the customer that you didn’t break something that wasn’t leaking when it pulled into the shop. So, what would you say? Tell me how you make customers understand why they can’t drive their car off your lot unless they pay you to fix it today.