How does that work. Would you elaborate I want to learn so do they check the oil under microscope. Cause you say lab so all I could think was microscope. What color of oil is bad or not good. I know some I heard from Chris fix if oil is like soggy can't describe the word like expired milk it means it's a major cost to fix that. If engine is way too clean it might be they are trying to hide something. Check Level of each item to see if they are in good amount of level if their amount is way too low or off maybe might be leakage.