Originally Posted By: demarpaint
In well over 30 years of car ownership. I've used Mobil 1 (over 20 years) as my only synthetic oil until late 2008 when I stopped using it. In conventional oils I used Valvoline for several years, Castrol, and Pennzoil. I used Pennzoil conventional more than any other oil, and found it to be the best conventional.
Upon joining BITOG, and owning a vehicle with over 150,000 miles I started switching brands a little, but still feel Pennzoil makes the best oil you can grab in a store. Any engine I owned that I took a valve cover off was always the cleanest with Pennzoil. But then again none of them were really dirty, from what I could see. MMO was used quite often too, so that could have helped keep them clean. JMO
Your engines ability to stay clean depended mostly on its own particular design, your oil changing habits, your driving habits and your environment.
The oil you used had about the smallest part in all of this. Most if not all modern oils will do exactly what you found in your engine.