When I first began my search, one of the biggest red flags appeared when a seller hesitated to provide any documentation for what he claimed was a reconditioned Audi Q5 engine. In real-world buying situations, reputable suppliers always present evidence of repairs, replaced components, and diagnostic results. The moment a seller avoids transparency, you’re likely dealing with someone hiding a worn-out unit disguised as something “freshly rebuilt.” During my inspection, the supplier kept repeating vague claims like “it’s fully done” yet had nothing to support it—not even compression test results. This instantly suggested the engine had either never been opened or had been worked on by an unqualified mechanic. If a seller can’t show paperwork, photos of the rebuild, or a clear service history, walk away immediately.