HEY JUST SIGN UP I OWN A 72DUSTER I6 225 AUTO TRANS GREAT  CONDITION,BUT SLUDGE BUILD UP I ONLY HAD THIS CAR FOR A WEEK ITS OWESOME IT DRIVES GREAT BUT I WANT TO GET RID OF SLUDGE, THINKING ON CHANGING THE OIL AND FILTER ONES A MONTH FOR THREE MONTHS ANYBODY KNOWS ABOUT ENGINE SENTRY,WHAT BRAND AND GRADE OF OIL DO U GUYS USED ON YOUR 70S DUSTER ENGINE,IT LOOK LIKE I HAVE A LOT OF WORK AHEAD OF ME .  

One thing that is very important is NOT to switch oils....even when adding to "top it off".
Sludge buildup is sometimes a problem with used cars because of the use of many different brands of oil over the years. Conventional oils come in 2 types....Pennsylvania grade and Texas grade.  The 2 grades do not mix well and the result is sludge.
Check with your local auto parts store on what they suggest as a good sludge remover. Next, pick a type of oil and stick with it.
You did not say how many miles the engine had. Lower miles go with a 10W30. Above 70,000 miles use a 10W40.
Hope this helps!http://forums.moparmusclemagazine.com/_siteconfigs/_global/images/community/bbcode/smile.gif  

Schaeffers oil, your climate will dictate the weight, I like 20-50w for where I'm at.
Check them out at Schaeffers oil.com  

Sludge is developed from some one making short trips, less than 20 min. drives, like many people do in the city. What do the short trips do?  Simple, cause condinsation to build up in your engine.
How do you get ride of the sludge? Its not that difficult, first make sure your vehicle is running at the proper eng.temp. anywhere from 180-195 is a good temp. for this engine to run at. How do you make sure this is the case? By installing a 180 or 195 thermostat in your vehicle.
Second make sure the vehicle sees some regular highway use, this will help get rid of the condinsation by allowing the engine to reach operating temp., plus use a quality oil, 10w30 or 10w40 depending on your climate and if the vehicle is using oil go with the 10w40.
If you are able to remove the valve cover and remove the white build up of sludge from inside the cover this will help get rid of the problem sooner. You may have to do this a couple of times over the next couple of months and I would recommend changing the oil every 1000/1500 miles until the problem clears up.