Seems like most people are disappointed with AutoRx when it comes to cleaning. ExxonMobil specifically states that their High Mileage oils, among other grades such as their 0w40, will clean up existing deposits and sludge.
http://www.mobil1.com.au/why/outstanding.aspx
http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_1_High_Mileage_5W-30.aspx
Quote:
Mobil 1 High Mileage is designed especially for engines where conventional oil has been used, and where these conditions have been experienced:
* Severe Service
* Extended Oil Drains
* Poor Maintenance
* Multiple Owners
For engines where heavy deposits and sludging exist, we recommend short initial oil change drain intervals of 3,000 miles as cleanup progresses.
http://www.mobil1.com.au/why/outstanding.aspx
http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_1_High_Mileage_5W-30.aspx
Quote:
Mobil 1 High Mileage is designed especially for engines where conventional oil has been used, and where these conditions have been experienced:
* Severe Service
* Extended Oil Drains
* Poor Maintenance
* Multiple Owners
For engines where heavy deposits and sludging exist, we recommend short initial oil change drain intervals of 3,000 miles as cleanup progresses.