There is another post here about Motorcraft 5W-20 motor oil displaying great UOAs. What about Motorcraft 5W-30 and 10W-30? Are they also great motor oils? These oils are actually produced by Conoco. Are Conoco motor oils kind of like Chevron motor oils-hidden gems? My Dad used to use Conoco motor oil. He told me that Mystik (which I guess they used in construction equipment and heavy trucks) was really a good motor oil, but he actually used Conoco. He had Conoco in his Ford Maverick car the day that he died.