Just put that stuff in one of my cars.. A 97 honda civic and draining it out at 5000 mile interval and planning on sending the oil out for analysis. My question is the car has roughly 56000 miles in it and never has seen synthetic. With conventional oil, I think I read somewhere that overtime, it might produce sludge inside the engine. Running synthetic I believe will clean out all that junk, but will it not also affect the analysis??