The Mobil 1 15w50 really cleaned out the inside of my engine when I first used it....and of course my driveway started looking a lot more like my basset hound

I was amazed at how clean that engine was on the inside...that synth. sure does its thing..(only after 3-5k miles on synth).

I haven't found anything harder to get off my hands/arms/skin yet than heavily used synthetic diesel motor oil