A few years ago, an employee of Valvoline Instant Oil Change was pushing an engine cleaning treatment on me, so I called my mechanic to see how he felt about it.

My mechanic informed me that allowing them to perform this "service" would ultimately cost me hundreds of dollars in engine damages within a few months. I don't recall what he said it would do to the engine, but I trust his opinion and didn't allow them to perform the service.

When I explained what my mechanic, (who's been a mechanic for approximately 30 years,) told me, this 18 to 20-year-old kid told me that my mechanic didn't know what he's talking about.