Why? MDS uses deactivating lifter that need 5W-20 to work properly. Otherwise, MDS may not work.
From AllPar, Oil grades and use. If you have the MDS system, be sure to use 5W20 oil - note that many dealers will use bulk 10W30 or even 10W40, partly out of ignorance and partly because it’s cheaper. You need to use the right oil if you want to keep your engine. Of course if the owner’s manual says something else, follow its advice - but don’t be convinced by a mechanic or oil-change place. Insist on the right grade and if they don’t use it...get a refund and go somewhere else. A technical service bulletin (TSB) - 09-015-04 and 09-013-04 - says: “Vehicles with the Multiple Displacement System must use SAE 5W-20 oil. Failure to do so may result in improper operation of the MDS.” Watch the mechanic pour it in! (This is said to be the real reason BMW provides free oil changes.)
Be prepared for a difficult to remove oil filter. The factory put them on with a dry gasket and over tightened. Finally found an oil filter wrench that looked like a big pair of channel locks. And we had the Ram on a lift and it still took me and a friend working together to get it off. So come prepared for battle or just take it to the dealer for your first change, make sure they do it right. Then after that you should be good to go on your own.
Bought my filter at Carquest. Make sure you get the one for the 2009 model year. It's different than earlier years.
Plus I installed MagnaFine engine and transmission filters that are good for about 30 to 50,000 miles.
Vehicle: 2010 Dodge Ram 1500 SLT 4x4 Hemi Big Horn edition with the 3.92's
Location: Bristol, NH
I have the 4.7 and they are recommending 5W20 in it as well. I figure since I get my oil changes for under 25 bucks and the first 6 oil changes free from the dealer, I will let them deal with getting to first filter and everyone after that off.
2010 Dodge Ram Crew Cab 4x4 SLT Big Horn Edition, 3.92 LSD, Mopar leveling kit w/BFG 34's Mopar 5" side steps, Dual Exhaust with Mufflex DOD24M mod.