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Was a Dodge Ram Harmed Since CJ-4 Oil Not Used
I have a 2001 Ram diesel truck with 57,000 miles on it. I've used Mobil 1 15W-50 since it had 500 miles on it. I will be switching to the new 5W-40 turbo diesel truck. Did I do harm to my engine because the 15W-50 was not CJ-4 certified?
-- John Suanno, Jackson, NJ
No. CJ-4 is a certification valid for 2007 and newer engines due to new EPA requirements. You should be fine.