Sorry if this has been discussed before but I am interested in finding out what type of oil is BEST at cleaning a dirty gasoline engine and keeping it clean. Lets say we are not interested at all in a long drain interval...just something conservative say 5,000 miles... Would one be better off using a premium OTC synthetic such as M1/PP or would one see just as good or better results using a HDEO such as Rotella T or Delo? I have always had the understanding that synthetics offer advantages under extreme hot/cold conditions and extended drain intervals but for the most part clean just the same as a modern conventional like PYB. With that said, I have been told over the years that HDEOs have superior cleaning abilities compared to even the name brand synthetics. Can anyone offer some first-hand experience on this topic?