Before you go back, do an oil change. When your oil turns dark it is not because of engine wear, it is because before your exhaust leaves the cylinder a certain amount goes past the rings and into the oil which makes it turn color to dark. When your piston goes back up, oil gets coated on the cylinder wall and burns with the gas. With emissions laden oil burning with the gas and going out in your exhaust, your emissions will read higher for the test.

A fresh oil change is the is a must for older cars before you make any mixture adjustments or emissions test for true accuracy.