Oils lubricate, they dont really clean.
High Mileage oils have better additive packs and that is what you pay for. They may clean some.
If you really want to clean take a look at Auto RX, or if you look to flush an engine try a few 1000 mile runs of SuperTech.
What are you trying to do? What car and mileage?
You will have better educated opinions with a little more data.
Isn't the Sodium present in an oil an indicator of its ability to "clean"?
I recall that Mobil Clean 5000/7500 have fairly high amounts of Sodium.
They are there to help keeps oil stay clean longer, not to aggressively clean other things out.
Like one of the good ole BITOGer used to say:
oil lubricates, not to clean.
Solvent cleans, but does not lubricate.
OK..Ive seen myself, pics here, of those who have used mobil1 synthetic, pulled the head off, and engine, bearings, valves, were factory new looking...
APparently, mobil1 does in fact, clean too well. IM just pointing this out.