2005 Grand Cherokee 3.7 engine (v6) 5w20 or 5w30?

Messages
682
Location
ontario canada
it is now specced for the 20 weight, i have the o8 Dakota with the 3.7l. probably i will run a 5w25 in it though. if i plan on a super long OCI then i will use a straight synthetic, otherwise i mix it 50:50 group3:group2+
 
Messages
35,000
Location
NY
In in 2007 they started using 5W20 oil for the 3.7L engine. I had checked today and Mobil actually suggests a 10W30 or 0W30 and makes no mention of 5W30 in their "Ultimate Oil" line up for that engine in 2005.
 
Messages
4,435
Location
Southeast
my '08 3.7L did not impress with M1. M1 5-20 was great for about 1800 miles but then started running like the FF at 3,000 miles. Vibration and valve tick. Dumped it around 4,500 and now PP 5-20 in there. It feels better, less of a "rumble" feeling and less noise, but only 1,000 miles on it so far. I personally feel that my particular engine would be better-suited for a x-30 weight, but the manual is a little vague as to what will and will not be suitable for warranty purposes. It does call out the MS-6395 criteria as needed for warranty, and I believe that some x-30s carry the ms-6395. M
 
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