Like a doctor who proposes "Non-Invasive-Diagnostics"
He does it from an adjacent room listening to a glass held against the wall
Can't turn the clock back on 160,000 miles. The best you can hope for is a worn out engine that somehow passes a smog test.
First of all a "Compression Test" is next to worthless: A "CYLINDER LEAKDOWN TEST"
Shifty sellers change the oil and use SAE 50 to reduce blue smoke and raise the oil pressure a smidge off the "Danger Low Oil Pressure" peg
Run your finger around the inside of the tailpipe. If it comes out black and oily - BAD. Remove top of air filter housing. Wet oily housing - BAD.
Remove dipstick. Smell it. Oil burners and compression leakers leave a telltale rank smell which is embedded in the varnish on the stick. A good engine's dipstick will smell like new oil.
Take a pocket B.S. detector. If it overloads and catches fire a block before your destination, turn around and flee.
