I’ve been sending you samples for five years. This report was the first one that spotted trouble. Sure enough, your diagnosis was spot on! It was a leaky intake gasket that was the most likely culprit, also causing the engine trouble light to come on. It seems the problem’s been cured. Should I change the oil again and send another sample after 2000 miles? How about using a synthetic? Again, great work guys.

Had to overhaul my 06 Columbia Freightliner. Thank goodness I took a one year warranty on it! Your samples provided the needed information that something was wrong with the motor. Had a leaking head gasket and two or three of the cylinder liners were leaking as well. Thanks for the good work.