I haven't checked the owner's manual in a while, I am on a Ram Forum and this has been a topic of discussion several times lately. Some say theirs run fine on 87 octane, some say they use 89 octane, and some, like me, run 93 octane. I just know my truck doesn't appreciate 87 octane. I'll check my owner's manual and see what it recommends and try to remember to let you know what I find.
