Engine Mechanical problem
2001 Suzuki XL7 4 cyl Two Wheel Drive Automatic 83000 miles

I started noticing a knocking noise with start up of my engine. Took to mechanic who stated that all oil had leaked out and was running on empty. He says I probably need new engine without doing any diagnostics and approximately $5000 of work. Could it be anything else and how much trouble am I in? Thanks.